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diff --git a/old/44569.txt b/old/44569.txt new file mode 100644 index 0000000..95b45d8 --- /dev/null +++ b/old/44569.txt @@ -0,0 +1,13071 @@ +The Project Gutenberg EBook of The Diatomaceae of Philadelphia and Vicinity, by +Charles Sumner Boyer + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: The Diatomaceae of Philadelphia and Vicinity + +Author: Charles Sumner Boyer + +Release Date: January 3, 2014 [EBook #44569] + +Language: English + +Character set encoding: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK DIATOMACEAE *** + + + + +Produced by Charlene Taylor, Bryan Ness, Keith Edkins and +the Online Distributed Proofreading Team at +http://www.pgdp.net (This file was produced from images +generously made available by The Internet Archive) + + + + + +Transcriber's note: Text enclosed by underscores is in italics (_italics_). + Page numbers enclosed by curly braces (example: {25}) have been + incorporated to facilitate the use of the Index. + +Images of the original pages are available through Internet Archive. See + https://archive.org/details/diatomaceofphi00boye + + * * * * * + +[Illustration: DUCK POND, CORNER OF FOURTH AND MARKET STREETS (ABOUT 1700)] + + + + +THE DIATOMACEAE OF +PHILADELPHIA AND VICINITY + + +BY + +CHARLES S. BOYER, A.M., F.R.M.S. + + +_ILLUSTRATED WITH SEVEN HUNDRED +DRAWINGS BY THE AUTHOR_ + + +PRESS OF + +J. B. LIPPINCOTT COMPANY + +EAST WASHINGTON SQUARE PHILADELPHIA + +1916 + + + + +PREFACE + + +The present contribution to the local flora is intended as an introduction +to more extended research. + +The study is of advantage in relation to the life history of aquatic +animals, the determination of ocean currents, as proved by polar +discoveries, the investigation of geological strata where other fossil +forms are absent, and the analysis of water supply; and, when we consider +the universal distribution of diatomaceae in the earth, the water and even +in the air and the enormous deposits formed in past ages and still forming, +we are able to realize the importance of a knowledge of these complicated +forms and their function of purification. + +The absence of descriptive works of reference in available form in this +country, the polyglot confusion of authorities abroad and the amount of +time, patience and skill required in obtaining, preparing and examining +specimens, render the study one of difficulty. + +The bibliography is omitted, as it is understood by those who possess the +works of reference, and but few synonyms are given, having but little, +except historical, value, especially when it is considered that modern +investigators have no access to many of the earlier collections, when any +of these exist. + +So far as the marine forms are concerned, it is probable that nearly all +occurring north of Florida are here included, and the fresh-water species +described represent a large proportion of those found east of the +Alleghanies. All of the figures are drawn to the same scale, a +magnification of eight hundred diameters, from specimens in my possession, +nearly all of which were found in or near Philadelphia. + +If the work is of any value in inducing further investigation, I hope, in +the words of Julien Deby, that "those who follow my advice will find in the +study of these wonderful little organisms as much pleasure as I myself have +found." + + THE AUTHOR. + + + + +{5}INTRODUCTION + + +The Delaware River rises in the Western Catskill Mountains, flows southward +for about three hundred and seventy-five miles, and expands into Delaware +Bay about sixty miles from the sea. Its origin is among the Devonian and +Carboniferous rocks, and in its course it passes through Silurian, Triassic +and Cretaceous formations, finally reaching the Cambrian and Laurentian +beds. It also drains regions of the glacial drift and beds which overlie +overturned Miocene strata, and are sometimes mixed with them. From the +mountains, nearly four thousand feet high, to the Bay, where the depth of +water is not greater than seventy-five feet, the diatomaceous flora, from +Alpine cascades to the salt marshes of New Jersey, contains a larger number +of species than any other equal portion of the American coast. + +The city of Philadelphia, about one hundred miles from the sea, lies at the +junction of the Schuylkill with the Delaware, and much of the land near the +rivers, especially southward, is flat and low, composed of recent alluvial +deposits. In the central districts the ground is high, the deep sub-soil +being mostly a dry gravel resting upon gneiss and schist, although it is in +part composed of a bluish clay which was probably laid down in the bed of +the ancient river before the last period of the glacial drift. The blue +clay was not all deposited at the same time, as in the lower strata many +marine forms are found which do not occur in the upper layers. This is +notably the case in a deposit obtained at Spreckel's Sugar Refinery and +also at the east end of Walnut Street Bridge, where a layer of blue clay +occurs which is overlain by glacial drift. In other parts of the city +mixtures of blue clay with more recent deposits are found, including +fresh-water forms from numerous creeks and rivulets which traversed what is +now the city proper, and especially from the vicinity of Fourth and Market +Streets, where there existed as late as the year 1700 a large pond known as +the "Duck Pond" which was subject to tidal overflow from its outlet, Dock +Creek. The river water at Philadelphia is not noticeably brackish, although +the tide extends thirty miles above the city and, before the building of +Fairmount Dam, to the Falls of the Schuylkill. At certain times, when the +river is low, the influx of tide water is sufficient to produce an +abundance of brackish water diatoms at Greenwich Point. The entire absence, +however, at present, of many of the marine forms obtained in dredgings in +the Delaware opposite the city, as at Smith's Island, now removed, and in +certain well borings at Pavonia, Pensauken, Gloucester and other places in +New Jersey, where the depth reached the old blue clay, indicates conditions +quite different from those now prevalent. In the Bay itself comparatively +few living species are found, at least in any abundance. + +In the study of local forms which follows, the district included may be +considered as circumscribed by the circumference of a circle having a +radius of one hundred miles from Philadelphia, containing the States of New +Jersey and Delaware, the southeastern part of {6}Pennsylvania, a portion of +Maryland on the south and extending eastward to New York Bay and Long +Island Sound as far as New Rochelle. + +The greater number of fresh-water species described have been obtained from +near the city along the Darby, Crum, Ridley and Brandywine Creeks and from +various places in New Jersey, including the Pine Barren region of the +southern part of the State. Numerous collections have been made in the +Schuylkill and the various reservoirs and along the Wissahickon, "where an +Alpine gorge in miniature of singular loveliness is to be found within the +limits of a city." The fossil deposits are from well borings near Camden, +N. J., and from excavations in various parts of the city. + +There appears to be no relation between the Miocene beds of the eastern +coast and the deposits here described, all of which have been formed later +than the glacial period or in an interval between two such periods. +Apparently no diatoms grew during the glacial era, at least in sufficient +abundance to leave any perceptible traces of their existence. An +examination of glacial "flour" and clays from the Catskills shows an entire +absence of these forms, and I have never found them in the milky flow from +the glaciers of the Alps nor in the constantly muddy streams in certain of +our Western States. The opacity of the water produces the same result as +the absence of light in the deep lakes of New England, where diatoms are +found only on the stalks or roots of water-plants near the shore, while in +shallow ponds, such as the small lake near the summit of Mt. Lafayette, the +growth is abundant. Certain species will grow wherever there are moisture, +light and heat, but the greater number require the presence, in small +amounts, of substances produced by the decay of animal and vegetable life. +An abundance of diatoms in fresh water is usually an indication of its +potability, while their entire absence in shallow water may be due to an +excess of bacteria. + +The specimens from which the drawings are made have been collected by the +author for many years; in addition to possessing an almost complete library +on the subject, he has had the advantage of examining material obtained by +the late Mr. Lewis Woolman and numerous slides furnished by a number of +friends, including Mr. John A. Shulze, Mr. Frank J. Keeley and Mr. T. +Chalkley Palmer, to whom I here take pleasure in expressing my thanks. + +The difficulties of the study are well stated by Agardh in the following +extract from the preface to his Systema Algarum: + +"Because, indeed, in this respect, no one will wonder whether in the +distinction of species and reference to synonyms we have, perchance, +committed many errors. They have occurred and are bound to occur, partly +from the fact that one is not permitted to see the original specimens of +all authors; partly, because sometimes even the original specimens of these +plants are erroneous; partly, because the figures and descriptions of +authors are often lacking and imperfect.... + +"There is added the difficulty of the study itself of these plants, their +submerged habitat, the minuteness of their structure, the rarity of their +fruit, the change in the dried {7}plant, the impossibility of culture, the +fallacies of microscopical vision and the chaotic condition of Algology +itself to-day." + +The words of Agardh, written in 1824, are almost as true to-day. The lack +of authentic specimens, which we hope will be remedied in time by the +collections of the Smithsonian Institute, numerous incorrectly labelled +slides in amateur collections, the imperfections of figures copied and +recopied, without regard to relative size or correct references, and the +confusion in the attempts to harmonize different descriptions, deter the +student at the outset. The remaining difficulties mentioned by Agardh add, +however, to the remarkable interest these forms have always had, since no +increase in optical perfection of the microscope serves to lessen the +mystery of their structure and mode of growth. + + +CLASSIFICATION + +The few species of diatoms first discovered were included by Lyngbye, +Dillwyn, and others in the genus _Conferva_. In 1824, the species, +increased to forty-eight, were separated by Agardh into eight genera +distinguished partly by their mode of growth. But little change was made +until Heiberg, in 1863, advocated the division into symmetrical and +asymmetrical forms. Without entering upon a general review of the later +classifications, including Pfitzer's and Petit's divisions according to the +number and location of the chromatophores, or the arrangement of Prof. H. +L. Smith, because of the presence or absence of a raphe, or that of +Mereschkowsky into motile and immotile forms, the modification of all of +these methods by Schuett is here adopted, varied in accordance with certain +monographs which appear to offer advantage. + +It is customary, especially among writers who are familiar with other +classes of plants, to decry any classification of diatoms according to the +markings of their siliceous envelopes. As, however, one of the chief +distinctions of the class is the possession of a more or less siliceous and +indestructible frustule, and as the cell and its contents are never seen +except within the valves, their variety forms the only available method of +identification. The cell contents, owing to the difficulty of observing +their living condition, their continued change, their lack of distinct +variation and their entire absence in fossil forms, render their +consideration as a complete method of classification an impossibility. If, +however, the cell contents can be brought into relation with the markings +of their siliceous envelope, it will be a consummation for which the future +student of these complicated forms ought to be grateful. That this result +is one to be expected may be inferred from the fact that the arrangement of +protoplasmic masses in the interior of the cell is coincident in some cases +with markings on the valve, and the character of the endochrome is assuming +a certain value in accentuating the difference between such forms as +_Pleurosigma_ and _Gyrosigma_, or in the resemblance between _Hantzschia_ +and _Nitzschia_, or between _Surirella_ and _Campylodiscus_. Mereschkowsky, +however, states that it is necessary to be careful in "establishing the +relationship between diatoms based on the resemblance of their +chromatophores," {8}and further observes that in _Hantzschia amphioxys_, +_Scoliotropis latestriata_ and _Achnanthes brevipes_, three widely +separated forms, the chromatophores are essentially the same. + +In one of the earliest classifications of diatoms, the individual cell +received less consideration than the nature of the filament or thallus in +which many species occur in the first stages of their growth. Those, +however, which exist in colonies at first are, sooner or later, broken up +into separate frustules, either before or at the time of their maturity or +previous to conjugation, while very many species are never seen except in a +free state. The union of frustules, therefore, is of secondary importance +and the group must be considered as filamentous or unicellular algae. Their +relation to other algae is not well determined. Among the _Desmidiaceae_, a +family of the order _Conjugales_, of the class _Chlorophyceae_, the cells +are in many forms divided by a constriction into symmetrical halves. The +Conjugales are starch forming, with walls of cellulose. In the Diatomaceae +the starch is replaced by oil globules, while the walls of cellulose are +more or less filled with a deposit of silica. The Conjugales, however, +reproduce by zygospores and usually contain pyrenoids, as may be seen in +the parietal chromatophores of _Spirogyra_. In the class _Heterokontae_ we +have the reserve material in the form of oil, instead of starch, but there +are no pyrenoids. To this class belongs the order _Confervaceae_, in which +the cells are unicellular or filamentous, and to which all of the +Diatomaceae were referred. While, therefore, Diatomaceae have a close +affinity to the Desmidiaceae and to the Confervaceae, the determination of +their origin, one from another, or from a common ancestral type, appears to +be a matter of conjecture. + + + + +{9}MORPHOLOGY AND DEVELOPMENT + + +THE CELL + +The cell membrane is composed of two usually equal parts, each of which +consists of a valve and a girdle or zone formed of cellulose modified by +silica deposited in an insoluble state from a very dilute aqueous solution. +The valves are more siliceous and robust than the girdle. Both are in most +species easily separable, or at least the bands of the girdle which may be +more or less closely fastened to the valves have a motion over each other +permitting the cell to enlarge at pleasure. The longitudinal diameter of +the cell, or the distance between the centres of the two valves, will vary +according to the convexity of the valve and the age of the frustule which +may be often determined by the width or number of the girdle bands. These, +owing to their diversity of form and arrangement, will be further described +under the generic diagnoses. + +The siliceous cell-wall is covered on the outside by a layer of protoplasm +called the coleoderm. This layer may be quite thin and evident only when +treated with fuchsin or Bismarck brown, or it may be of considerable +thickness. The cell contains the cytoplasma, protoplasm, cell-sap, +endochrome, pyrenoids, oil globules and nucleus, together with certain +other less understood bodies. + +The Cytoplasma is a thin skin of colorless plasma covering the entire inner +surface of the cell. It is invisible in the living cell but is evident in +plasmolysis. In long forms it is thickened at the ends and is condensed at +the plasma bridge which frequently connects the two valves and divides the +cell into two parts, each containing more or less protoplasm surrounding +the vacuole in which are found the cell-sap and certain granules. In some +forms, as Meloseira, the cytoplasma includes the entire mass of protoplasm. + +The Endochrome is seen in the form of one or more bands or plates, of a +yellowish or brownish color, on the inner side of the valves or connective +zone, or in granules or irregular masses, more or less numerous, on the +inner walls, or sometimes grouped near the centre. It consists of a mixture +of chlorophyll and diatomine which differ in their relative solubility in +alcohol and in their spectroscopic analyses. The color varies from green to +a chocolate brown in proportion to the amount of diatomine. So far as the +function of the endochrome is concerned it does not appear to differ from +that of ordinary chlorophyll, absorbing, under the influence of light, the +carbon, and disengaging the oxygen of the carbonic anhydride in the water. +Diatoms do not live in absolutely pure or non-aerated water. The individual +plates or granules of the endochrome are called chromatophores. Their +number and significance will be referred to in the description of genera. + +THE PYRENOIDS.--In the chromatophores of many species are found colorless, +homogeneous bodies, strongly refractive, of various shapes, usually +lenticular or fusiform, which are known as Pyrenoids (Schmitz). They are +scarcely evident in the living cell, but are distinguished by the action of +haematoxylin and other reagents. Flat forms occur in Surirella and +Pleurosigma, lens forms in Pinnularia, Stauroneis, Synedra, Fragilaria and +Nitzschia, while a spherical form is found in Cymbella cuspidata. The +pyrenoids are always imbedded in the chromatophore. Their growth is by +division. Schmitz considers them a part of the living chromatophore, and +their substance as working material which in excess has become resolved +into the nature of a crystal which its form sometimes resembles. +Comparisons are made between them and crystalloids found in certain +monocotyledons. The pyrenoid is evidently concerned in the formation of the +chromatophore, or in its division. Much of the conjecture, however, is due +to the behavior of pyrenoids in other plants. + +{10}OIL GLOBULES.--It has been established by Pfitzer that starch and +sugar, as assimilation products, are replaced by oil in the cells of +diatoms ("da bekannlich Staerke und Zucker bei den Bacillariaceen nicht +nachzuweisen sind"). The oil drops are more or less numerous, of various +sizes, and are found in the cytoplasma, the cell-sap, and sometimes the +chromatophores. Mereschkowsky describes certain globules as elaeoplasts, +which he divides into four kinds according to their number and position. +Whether all of these are oil globules is a question not yet determined. + +Other bodies, known as "Buetschli granules," or volutin, and described as +"little blisters filled with a tolerably robust refractive substance," are +considered by Lauterborn to be a nitrogen reserve store. They are found in +the cytoplasma, or in the cell-sap, and can be fixed in picric acid and +stained in methylene blue. + +NOTE.--For a discussion of the morphology of diatoms and a valuable resume +of the investigations of Buetschli, Karsten, Lauterborn, Mereschkowsky, +Mueller, Pfitzer, Schuett, and others, the student is referred to "Der Bau +der Diatomzelle," by Dr. Otto Heinzerling, in "Bibliotheca Botanica," 1908. + + +CELL DIVISION + +The growth of diatoms follows the usual method of cell division as +described by Sachs (Text Book of Botany, 2nd ed., p. 16): "The nucleus of a +cell which is about to divide becomes broader, assuming the form of a +biconcave lens, and its nucleolus breaks up into irregular granules which +together with its other granular contents begin to form a nuclear disc in +the equatorial plane. A delicate striation is now apparent in what is +becoming the long axis of the nucleus, at right angles to the nuclear disc, +and the characteristic nuclear spindle is gradually produced. The nuclear +disc splits into two halves lying side by side, each of which travels to +the corresponding pole of the nucleus; thus two nuclei are constituted +which are connected by fibrillae." + +The cell-wall and the chromatophore bands divide, each nucleus passes to +the centre, and two new cells are formed. In the meantime, to permit of +this division, the two siliceous valves separate, the girdle bands slipping +over each other, and opposite the larger or enclosing valve a new valve is +formed, the girdle band of which is seen later within the girdle of the +mother valve. Opposite the smaller valve of the original cell and adjoining +the new valve, another valve is formed which also produces a girdle within +the girdle of the smaller valve. As a result of division we have, +therefore, the valves of the original, or mother cell, the two new valves +and four girdle bands. (Pl. 40, Figs. 18 and 19.) + +In the process of division, the continual formation of new valves, enclosed +in the older girdle bands, will naturally cause a reduction in the size of +the frustule. While this reduction, owing to the elasticity of the girdle, +does not always occur, I believe, yet, in most cases, the diameter is so +reduced that a rejuvenescence of growth is required. This is caused by the +production of auxospores which may appear without conjugation. In this +process, the beginning of which, in certain species, may be noticed by the +increase in the size of the girdle as in reduplication, the two valves +separate and within is formed a more or less spherical mass about twice the +size of the original frustule and which forms on its circumference two +large and often shapeless valves. These valves form others which assume the +appearance of the original valves, but larger, and proceed to grow in the +usual way. The reduction in size of the frustule seldom proceeds further +than about half the size of the type form, so that, as a general rule, it +may be stated that diatoms are not often smaller than half the larger size. + + +REPRODUCTION + +The process of reproduction has been observed in many cases, but the +conclusions reached are somewhat at variance with each other. The auxospore +formation is simply a {11}method of rejuvenescence. When, however, the +auxospores are thrown off from filamentous diatoms, it is probable that two +may conjugate, their contents dividing each into two daughter cells which +unite into two zygospores. The usual method is the union of two frustules, +which, throwing off the old valves, coalesce into a single mass of +protoplasm which produces an auxospore, sometimes called a sporangial +frustule. It is stated that in some cases two frustules coalesce and +produce two auxospores. + +The existence of spores in diatoms is a much-disputed point. While they +have never been seen, the inference that they exist is very great, as +otherwise it becomes difficult to understand the sudden growth of species +in localities and under conditions that seem to preclude the actual +presence of the living frustule. It is a matter of common observation that, +in examining collections of living forms, minute frustules or brownish +globules appear to resemble larger diatoms. In gatherings of Gomphonema, +when many specimens are sessile on the same object, numerous intermediate +sizes, varying from minute globules to the type, are seen, yet not +positively demonstrable as the same. + +Conjugation, the formation of auxospores, and the actual process of cell +division are seldom seen, as they occur during the night or at least in +darkness. It is advisable in order to observe reduplication to obtain the +material about midnight and place it in very dilute alcohol. In filamentous +forms, however, the cell division is easily observed at any time in its +various stages. By immersing in picric acid (saturated solution), +transferring to very dilute alcohol which is gradually increased in +strength, and then passing through oil of cloves and finally to the +mounting medium, excellent preparations can be made. By staining with gold +chloride alone the nucleus is made apparent without further treatment. + + +EVOLUTION OF FORMS + +It may be assumed that diatoms originated in the sea; to deny this requires +evidence of the existence of fresh-water species previous to the Miocene +period which is entirely marine. In those subject to fluctuations of the +waves, as pelagic diatoms, their existence appears to be contingent upon +the methods by which the separate frustules can cohere. Various devices, +including hooks, spiral bundles, horns and processes exuding threads of +plasma, exist for holding together the frustules. When marine forms are +found in quiet waters some of these devices, being no longer of any value, +cease to grow, although free swimming diatoms are rare. They either occur +in long chains or are stipitate or sessile. If it is further assumed that +the fresh-water diatoms are found in greater abundance in later periods, +the action of running streams makes necessary the provision of some means +by which the species may continue to colonize. This may be recognized in +the occurrence of linear forms chiefly in streams. Circular forms, such as +Cyclotella which have no raphe, are found in quiet waters, such as pools or +ditches, and never exist living in running streams. Those forms only would +be able to live in water having a more or less swift current under one of +three conditions: they must, as in Gomphonema, be adherent to surrounding +objects by a stipe; or be enclosed in a gelatinous tube, as in +Homoeocladia; or have an independent motion powerful enough to overcome the +influence of the current. It is true that many forms with a raphe have no +apparent motion. In the case of Mastogloia provision is made in a +gelatinous cushion in which the frustules are preserved. In Cocconeis, with +a true raphe in one valve only, in Epithemia, with a partial raphe, or in +certain Eunotiae with a trace of one, we find species evidently degenerate +and parasitic. The long Synedrae, having only a median line, live in +running streams, since they are attached at one end to other algae. Forms +with a true raphe appear to be more highly developed, since they are able +to seek locations favorable to growth. Given, therefore, the structure of +the valve, the habitat may be inferred. + + +{12}THE MOTION OF DIATOMS + +The erratic backward and forward movement of certain diatoms, especially +those of the Naviculoid group, or the slow, rolling motion of Surirella, +has been discussed in so many ways without definite conclusions that a +brief statement will be sufficient. Osmosis, the amoeboid movement of the +coleoderm, the protrusion of protoplasm or protoplasmic threads through the +raphe, the existence of actual organs of locomotion or cilia, and the lack +of synchronism in the chemical action occurring at the ends of the cell +which is sometimes divided by the plasma bridge, have been offered in +explanation. The chief objection to the theory of cyclosis appears to be +that the resultant motion is so greatly in excess of the rotation of +protoplasm in the cell. More or less motion is observed in various kinds of +free cells, but the movement of diatoms is not evident in those without +either a raphe or a keel upon which and apparently by which the phenomena +are produced. + +Mr. T. Chalkley Palmer, in various articles in the Proceedings of the +Delaware County Institute of Science, especially in Vols. 1 and 3, gives +the results of exhaustive experiments. "Nothing, it would seem," he says, +"could be more conclusive as to the essential sameness of the nature of +motion in monads and diatoms, than the fact that both monads and diatoms +require oxygen in order to perform motion, that they come to rest when +oxygen becomes scarce, and that they resume their motion when oxygen is +again supplied." + +He also thinks "that the living substance of the cell, more or less deeply +overlaid with coleoderm substance of varying consistency, and itself +assuming that degree of fluidity which best meets the requirements of the +situation, permeates the raphes, circulates in the keels, or in some cases +protrudes quite beyond the silica, and functions as the actual propulsive +agent." + + +THE FUNCTION OF DIATOMS + +Of all forms of vegetation, the Diatomaceae are, perhaps, the most +ubiquitous. Where-ever a sufficient amount of moisture, heat and light are +found, they grow. It was during the Miocene period that they first +appeared, and, as marine forms, reached their greatest development, both as +to size and beauty of marking, while their prevalence throughout the world +in enormous quantities has been often mentioned. The Miocene beds of +Richmond and Maryland continued over the Cretaceous formations of New +Jersey have outcropped in certain localities within our district, but are +not considered in this discussion. + +The function of diatoms is not essentially different from that of other +algae in providing food for aquatic animals, such as Salpae and oysters, +but it is, however, in other respects that they are not only important but +necessary factors in the preservation of life. + + "Full nature swarms with life; one wondrous mass + Of animals, or atoms organized, + Waiting the vital breath, when parent heaven + Shall bid his spirit blow. The hoary fen, + In putrid streams, emits the living cloud + Of pestilence. Thro' subterranean cells + Where searching sunbeams scarce can find a way, + Earth animated heaves." + +I am not certain if Thomson fully understood the matter, but he has +remarkably described the facts. When "the vital breath" of returning spring +animates the earth, the "subterranean cells" of diatoms, the "atoms +organized," through the liberation of vast quantities of oxygen, +immediately begin the purification of the "putrid streams." Were these +streams not so purified, the accumulation of animal and vegetable debris +would eventually cause an enormous bacterial growth fatal to animal life. + + + + +{13}DIATOMACEAE + + +Unicellular or filamentous. Cells either free, sessile, united in +filaments, immersed in a gelatinous envelope or in fronds composed of +branching tubes; microscopic, enclosed in a more or less siliceous envelope +(frustule), composed of two parts (valves), usually connected by an +intervening band (zone or girdle). Cell contents include yellowish or +brownish chlorophyll-like bodies which occur in one or several bands +(placcochromatic), or as variously distributed granular masses +(coccochromatic) lining the inner walls. Growth by ordinary cell division +or by auxospores; sexual multiplication by the formation of sporangia. +Valves of two kinds: (_a_) Those in which the markings or parts are more or +less concentric (Centricae); (_b_) Those (Pennatae) in which the parts are +more or less symmetrically divided by a line (pseudoraphe) or by a cleft +(raphe). + + + +CENTRICAE + +Valves without a dividing line or cleft; markings more or less radiate; +transverse section of frustule circular, polygonal, or elliptical, +sometimes irregular. + +Divided into four groups: + +1. _Discoideae._--Frustules (cells) discoid; valves without horns or +elevations (sometimes with processes). + +2. _Solenoideae._--Frustules with numerous girdle bands. + +3. _Biddulphioideae._--Frustules box-like, _i. e._, with the longitudinal +axis greater than in the Discoideae. Valves with two or more angles, +elevations or horns. + +4. _Rutilarioideae._--Valves as if naviculoid, but with irregular or radial +structure. + +Groups 2 and 4 are not included in our description. No. 2 contains plankton +genera only, while No. 4 consists of genera not yet found in this locality. + + + +DISCOIDEAE + +1. _Coscinodisceae._--Valve not divided by rays or costae into sectors; +puncta sometimes radiate; ocelli or processes absent. + +2. _Actinodisceae._--Valve with radial striae divided into sectors: ocelli +and processes absent. + +3. _Eupodisceae._--Valve disc-shaped with mammiform processes or one or +more ocelli. + + + +1. COSCINODISCEAE + +(_a_) _Meloseirinae._--Frustules short, in chains. + +(_b_) _Coscinodiscinae._--Frustules disc form, usually single, rarely in +short chains. + + + +(_a_) MELOSEIRINAE + +1. _Meloseira._--Valve punctate, with a constriction or furrow between edge +of valve and girdle. + +2. _Gaillonella._--Valve punctate, with a circular collar or crest near +edge of valve. + +3. _Lysigonium._--Valve punctate, neither keeled nor constricted. + +4. _Hyalodiscus._--Valve punctate in the centre; border with decussating +radial lines. + +5. _Stephanopyxis._--Border of valve with a crown of thorns; valve +areolate. + +6. _Pyxidicula._--Valve areolate, with a border of spines. + + +{14}MELOSEIRA AG. (1824), em. DE TONI (1892) + +(melos, a limb or member, and seira, a chain) + +Frustules globose, ellipsoidal or cylindrical, concatenate, closely joined +together. Valve either simply punctate or punctate and areolate. A +constriction of the cell-wall, forming a furrow between the edge of the +valve and the girdle, is more or less evident. + +The genus Meloseira constituted by Agardh has been variously modified by +Kuetzing, Thwaites, Wm. Smith, Van Heurck, De Toni, and others. In Systema +Algarum Agardh included certain species of Conferva, of Lyngbye, Dillwyn +and others, and limited his genus to frustules more or less globose (fila +articulata ad genicula constricta), although in his Conspectus Criticus (p. +64), he modifies the description (fila teretia articulata, articulis +diametro aequalibus vel longioribus) to include M. varians. As, however, +Lysigonium Link, Gaillonella Bory, and other genera enlarged by Ehrenberg +and Kuetzing, came to be included under Meloseira, Thwaites suggested the +division of the genus into two: Orthosira, in which the frustules are not +convex at the ends and Aulacosira in which no central line is apparent but +with two distinct sulci. Wm. Smith adopts the genus Orthosira but rejects +Aulacosira, including all forms under the former genus and Meloseira, +suggesting that differences "exist in the formation of the sporangia" of +the two genera. M. varians and M. crenulata appear to form auxospores or +sporangial frustules in different ways, as will be noticed hereafter. + +As, however, the present state of our knowledge is so limited and as much +confusion would result in further changing the nomenclature, I shall adopt, +for the most part, the division made by De Toni, separating Gaillonella and +Lysigonium and employing the name Meloseira as emendated in Sylloge +Algarum, although, as stated, it omits the species of Agardh. That a +further division may be necessary is indicated by the differences existing +between the Orthosira forms and the others. + + +ANALYSIS OF SPECIES + + + Frustules cylindrical and lengthened: + + Valves with two distinct furrows; granules small distans + + Valves with coarse granules granulata + + Valves denticulate on the margin crenulata + + Valves denticulate and constricted roeseana + + Valves with row of large puncta on the girdle side undulata + + Frustules cylindrical and compressed: + + Valves punctate and areolate sulcata + +The chromatophores consist of circular and compressed or irregular flat +granules which lie along the wall of the cell. + + +MELOSEIRA DISTANS (EHR.) KUETZ. + +Frustules cylindrical, slender, with two furrows, one on each side of the +suture; valve in zone view with fine puncta in longitudinal rows; puncta in +valve view scattered. L. 7-10 [mu]. + +_Meloseira nivalis_ Wm. Sm. + +_Coscinodiscus minor_ Wm. Sm. + +Fresh water. Fossil in New England deposits. + +Pl. 1, Figs. 8 and 9. + +NOTE.--In all species of Meloseira, as well as Gaillonella and Lysigonium, +the frustules are so closely coherent that when the filaments are broken +entire frustules are less frequently found than a union of two valves of +contiguous frustules. + + +{15}MELOSEIRA GRANULATA (EHR.) RALFS + +Frustules cylindrical, robust, 5-18 [mu] in diam., with large granules in +longitudinal, sometimes spiral, lines, variable in size and arrangement in +the same filament. Valve in valve view with scattered puncta. Variable in +relative width and length, passing to M. crenulata. + +_Gaillonella granulata_ Ehr. + +_Orthosira punctata_ Wm. Sm. + +Fresh water. Fossil at Coldspring, L. I. + +Pl. 1, Fig. 10. + + +MELOSEIRA CRENULATA (EHR.) KUETZ. + +Frustules cylindrical, with furrows on each side of the suture, 10-20 [mu] +in diam.; puncta in longitudinal rows. Margins of valves denticulate at the +junction of the frustules; valves with puncta scattered at the centre, +radiate at the circumference. + +Common in fresh water; quite variable in size. + +_Gaillonella crenulata_ Ehr. + +_Orthosira orichalcea_ Wm. Sm. in part; not Conferva orichalcea. Mertens or +Gaillonella aurichalcea Ehr. and Bailey. + +Pl. 1, Figs. 1 and 2. + + +MELOSEIRA ROESEANA RAB. + +Frustules cylindrical, constricted toward each end, with coarse, +longitudinal striae; valve convex, striae punctate, radiating, with several +large granules at the centre. Connective zone with longitudinal rows of +fine puncta. Diam. 12-45 [mu]. + +_Orthosira spinosa_ Grev. + +Fresh water. Media, Pa. (Palmer); not common. + +Pl. 1, Figs. 5 and 6. + + +MELOSEIRA ROESEANA VAR. EPIDENDRON (EHR.) GRUN. + +Frustules denticulate at the margin; valve with coarse granules at the +centre from which radiate lines of fine puncta. + +Wet rocks of the Wissahickon. + +Pl. 1, Figs. 3 and 4. + + +MELOSEIRA UNDULATA (EHR.) KUETZ. + +Frustules single or in twos, usually broader than long, constricted near +the margin. Valve with six to twelve internal projections forming with the +outline of the constriction of the valve a polygonal figure within the +circumference. Surface of the valve with radiating lines of puncta +disappearing toward the centre, at which are numerous coarse puncta. + +_Meloseira gowenii_ A. Schmidt. + +Blue clay of Philadelphia, especially common at Twelfth and Market Sts. + +Pl. 1, Figs. 15, 16, 17. + + +MELOSEIRA SULCATA KUETZ. + +Frustules quite robust, with diam. several times the length, deeply +furrowed at the margin, areolate and punctate. Valve with radiating striae +disappearing toward the centre, and with a double row of cells near the +margin, the outer one having the appearance of a crown of teeth. + +_Gaillonella sulcata_ Ehr. + +_Paralia sulcata_ (Ehr.) Cleve. + +_Paralia marina_ Heib. + +{16}Marine and brackish. Common in all parts of the world, and fossil in +the Miocene. The Philadelphia form is the var. genuina Grun. + +Pl. 1, Figs. 11 and 12. + +In a gathering from Media of Meloseira crenulata (Palmer leg.), occasional +filaments are noticed with much longer and narrower frustules which become +enlarged in the middle and are seen to contain inner frustules in the +process of still further division, as shown in Fig. 2, Pl. 38. + +Meloseira dickei Thwaites shows internal box-like cells placed one within +the other, which were supposed by Thwaites to be a method of reproduction. +Wm. Smith doubts this, but is unable to offer any explanation. In the +present form the mode of reduplication is that usually found in filamentous +forms, but in this case the presence of perfect frustules enclosing others +in the process of still further division has been heretofore unfamiliar to +me. The swelling in the middle appears to indicate that not all filamentous +diatoms are reduced in size by subdivision. In outline the valve is like +that of a "truncated cone," as described by Petit in referring to +Gaillonella granulata var. bambusina Petit (Diat. Nouv. et Rares, Jour. de +Micrographie, 1890). + + +GAILLONELLA BORY DE ST. VINCENT (1823) + +(named after Gaillon, a botanist of Dieppe) + +Frustules ellipsoidal, united in long filaments, usually found in pairs; +each valve is furnished with a circular collar or crest extending at right +angles to the convex edge. Valve hyaline at the centre from near which +radiate lines of fine puncta, 18-20 in 10 [mu]. + +NOTE.--The original names of both Meloseira and Gaillonella are retained, +as there is no good reason for contracting the Greek diphthong in the +first, and the second is the correct spelling. + + +GAILLONELLA NUMMULOIDES (DILLW.) BORY + +Frustules as in the generic diagnosis. Diam. 30 [mu]. + +_Conferva nummuloides_ Dillwyn (Brit. Confervae, p. 45, Sup. Pl. B). + +_Meloseira nummuloides_ Ag. + +Heiberg and O'Meara assign this species to _Lysigonium moniliforme_ +(Muell.) Link, which is not keeled. While Dillwyn's and Lyngbye's figures +do not show the keel, it is probable from their descriptions that the +angular outline produced by the keel was noticed. + +Marine or brackish. Coast of New Jersey; Hudson River (Bail.). + +Pl. 1, Figs. 13 and 14. + +_Gaillonella moniliformis_ of Bailey is this form, as he describes it as +having "two minute projections of the delicate transverse ridges seen near +the ends of the two globules belonging to a joint." (Amer. Jour. Science, +1842, p. 89, Pl. 2, Fig. 3.) + + +LYSIGONIUM LINK (1820) + +(luo, to loose, and gonu, a joint) + +Frustules globose, concatenate; valve simply punctate. + + +LYSIGONIUM MONILIFORME (MUELL.) LINK + +Frustules usually in twos, not keeled; valve with puncta in longitudinal +lines, the puncta of the enveloping zone larger and in transverse rows. L. +25-40 [mu] (De Toni). + +_Conferva moniliformis_ Mueller (1783). + +{17}_Conferva nummuloides_ Eng. Bot. pl., 2287, not Dillwyn. + +_Meloseira borreri_ Grev. + +_Lysigonium nummuloides_ (Lyngb., Kuetz.) O'Meara = _Gaillonella +nummuloides_ (Dillw.) Bory. See O'Meara, p. 248. + +Marine and brackish. Long Island Sound and coast of New Jersey. + +Pl. 1, Fig. 7. + + +LYSIGONIUM VARIANS (AG.) DE TONI + +Frustules cylindrical, in long filaments, slightly constricted on each side +of the suture; puncta in oblique rows in zone view. Valves 15-35 [mu] in +diam. (De Toni), sub-plane, with fine puncta in lines radiating from the +centre. Under medium magnification the frustules appear smooth. Very +variable in size. + +_Meloseira varians_ Ag. + +Fresh water. Common in ditches and springs. + +Pl. 1, Figs. 18 and 19. + + +HYALODISCUS EHR. (1845) + +(hyalos, transparent, and discus, a disc) + +Frustules spheroidal; valve with a flattened, irregularly punctate +umbilicus from which proceed radiating or decussating lines of fine puncta. + + +ANALYSIS OF SPECIES + + + Valves divided into sectors stelliger + + Valves not divided but interrupted by short dark lines at + intervals radiatus + + Valves with very fine puncta scoticus + + +HYALODISCUS STELLIGER BAIL. + +Valve with puncta in oblique decussating rows which, by reason of the +difference in obliquity, form numerous sectors. Umbilicus irregular, with +scattered, coarse puncta. Margin wide, striated. + +_Podosira maculata_ Wm. Sm. + +Blue clay. Not common. + +Pl. 1, Fig. 22. + + +HYALODISCUS RADIATUS VAR. ARCTICA GRUN. + +Valve with radiating puncta from a rather small umbilicus, the rays +interspersed with short, dark lines, having the appearance of spines, at +irregular intervals. Margin broad, striated. + +_Pyxidicula radiata_ O'Meara. + +The Philadelphia form corresponds exactly to Grunow's variety which has +closer puncta than the type form. + +Blue clay. Rather rare. + +Pl. 1, Fig. 21. + + +{18}HYALODISCUS SCOTICUS (KUETZ.) GRUN. + +Valve small, with puncta about 24 in 10 [mu], appearing hyaline. + +De Toni remarks that it resembles a small form of H. subtilis which occurs +north and south of our limits and is yet likely to be recorded. + +_Cyclotella scotica_ Kuetz. + +_Podosira hormoides_ Wm. Sm. + +Blue clay. Not rare. + +Pl. 1, Fig. 20. + +Endochrome in the form of four flaps or patches bound together about a +common pyrenoid. In H. subtilis numerous rod-shaped chromatophores lie in a +row and are not bound in the centre (Mereschkowsky). + + +STEPHANOPYXIS EHR. (1844) em. GRUN. (1884) + +(stephanos, a crown, and pyxis, a kind of vase or box) + +Frustules ellipsoidal, concatenate; valves tumid, of unequal convexity, +coarsely areolate, the cells in rows parallel to the longitudinal axis, not +radiate, with stray spines or teeth placed concentrically more or less near +the margin. + +According to Karsten the chromatophores are round or angular discs which +lie near the connective zone. + + +STEPHANOPYXIS TURRIS (GREV.) RALFS + +Valve cylindrical, with a crown of stout spines less than the diameter of +the valve near the margin. Cells hexagonal, about 2 in 10 [mu], sometimes +punctate. The valve having the greater convexity has the larger spines, +though usually less of them. + +_Creswellia turris_ Grev. (Gregory, Diat. of the Clyde, T. R. S. E., vol. +21, part 4, p. 66.) + +_Stephanopyxis appendiculata_ Ehr.? + +Creswellia is incorrectly based, as stated by Ralfs, on the concatenation +of the valves which was not noticed by Ehrenberg in the fossil forms. It +had been suggested by Kuetzing in Systema Algarum (p. 126). + +Blue clay. Port Penn and Smith's Island. + +Pl. 2, Figs. 1 and 2. + + +STEPHANOPYXIS CORONA (EHR.) GRUN. + +Valve larger than in turris, sub-globose, coarsely areolate cells, 4-5 in +10 [mu]. One valve furnished with a crown of teeth shaped like the letter T +and united at the top into a ring above the margin of the valve; the other +valve with long spines more or less concentrically arranged. + +Blue clay. Not common. Fossil in the Nottingham deposit. + +Pl. 2, Fig. 3. + +NOTE.--The diatomaceous deposit, so often called "Bermuda" or "Bermuda +tripoli," especially by foreign writers, is in reality the Miocene stratum +extending for miles along the Patuxent River near the village of +Nottingham, Md. The author is perfectly familiar with the location, having +made large collections there. The mistake in the name is due to the fact +that Prof. Bailey received material from Mr. Tuomey marked "Bermuda +Hundred," which is located near Petersburg, Va. Attempts have been made to +find material there and while there is an earth containing Miocene diatoms +at Petersburg, it does not exactly correspond to the material sent to +Ehrenberg by Bailey, who was in doubt as to the locality. The Bermuda +Islands are of coral formation and have no deposits of diatomaceous earth. + + +{19}PYXIDICULA EHR. (1833) + +(dim. of pyxis, a box) + +Frustules globular, solitary or in short fasciae. Valve more or less +hemispherical, areolate, destitute of spines. + + +PYXIDICULA CRUCIATA EHR. + +Valve hemispherical, with large, hexagonal cells. An inner stratum is +finely punctate. + +Blue clay. Walnut St. Bridge. Rare. + +Pl. 38, Fig. 8. + +This form is not usually described as having punctate areolae, but it does +not apparently differ from other forms of Pyxidicula of Ehrenberg as +described by Kuetzing (Species Algarum, pp. 21-23), including _P. +areolata_. In fact, it differs from Stephanopyxis, which is also sometimes +punctate, only in the absence of spines. In fossil deposits the absence of +an easily detached stratum is not significant. The difference, except in +size, between it and _P. mediterranea_ Grun. (V. H. S., Pl. 95, Figs. 15 +and 16), I am unable to determine. + +Although many species of Meloseira are fresh-water, the habitat of the +group Meloseirinae is, in general, marine. It more nearly coincides in +structure and development with other algae not diatomaceous, the siliceous +envelope constituting its most distinctive feature. As we proceed in the +classification, the structure both of the frustule and contents becomes +more complicated. + + + +(_b_) COSCINODISCINAE + +1. _Cyclotella._--Valve with two concentric divisions of different +structure, one a wide border and the other a central surface. + +2. _Coscinodiscus._--Valve areolate or punctate, with a narrow border of +the same structure. + + +CYCLOTELLA KUETZ. (1833) + +(cyclos, a circle) + +Frustules single or geminate, cylindrical, short, in zone view rectangular +or with undulating sides. Valve usually with smooth or punctate striae, +centre sometimes bullose, smooth, or with granules scattered or radiating. + +Chromatophores numerous along the valves (Pfitzer). + + +CYCLOTELLA STRIATA (KUETZ.) GRUN. + +Valve 30-80 [mu] in diam., with coarse striae, 7-12 in 10 [mu], centre +coarsely punctate and bullose. + +_Coscinodiscus striatus_ Kuetz. + +_Cyclotella dallasiana_ Wm. Sm. + +Common in the blue clay. + +Pl. 2, Fig. 9. + + +CYCLOTELLA MENEGHINIANA KUETZ. + +Frustule in zone view rectangular, undulated; valve, 10-20 [mu] in diam., +marginal striae robust and transversely punctate, centre radiately +punctate. + +_Cyclotella kuetzingiana_ Wm. Sm. (not Thwaites). + +Crum Creek. + +Pl. 2, Fig. 8. + + +{20}CYCLOTELLA MENEGHINIANA, VAR. STELLIGERA CL. AND GRUN. + +Differs from the type in the coarse radiating lines at the centre. + +Broomall Lake, Media. + +Pl. 2, Fig. 4. + + +CYCLOTELLA MENEGHINIANA, VAR. STELLULIFERA CL. AND GRUN. + +As in type but with the central rays granulate. + +Broomall Lake, Media. + +Pl. 2, Fig. 12. + + +CYCLOTELLA STYLORUM (BR.?) V. H. + +Margin striated, the alternate striae thickened near the border, producing +an appearance of subquadrate cells. Centre faintly granulate, the outer +border of which is encircled by 10-12 puncta, each of which is surrounded +by a small hyaline space. + +Blue clay. Rare. + +Van Heurck gives this form doubtfully as a variety of _striata_, while De +Toni makes it synonymous with it. Van Heurck's figure is not that of +Brightwell, but as the specimen above described is, I believe, exactly the +same as Van Heurck's, I retain his name. + +Pl. 2, Fig. 10. + + +CYCLOTELLA COMTA (EHR.) KUETZ. + +Valve with marginal striae well marked, each third or fourth costa more +robust than the others. Central part finely striated, the striae punctate, +radiating. + +Fresh water. + +Pl. 2, Fig. 7. + +The form here figured is probably the variety _radiosa_ Grun. and is from a +New England specimen. It is quite likely to occur in this locality. + + +CYCLOTELLA OPERCULATA (AG.) KUETZ. + +Frustules in zone view undulated. Angles rounded. Marginal costae +alternating with minute spines; centre nearly smooth, depressed, convex or +flexuose. + +Fresh water. + +Pl. 2, Figs. 5 and 6. + +The figure is drawn from a specimen from Boston, Mass., H. L. Smith Type +Slide No. 107, marked equivalent to _C. minutula_ Wm. Sm. + + +CYCLOTELLA ANTIQUA WM. SM. + +Marginal costae alternating with thick puncta; centre finely granulate with +subtriangular elevations. Frustules in zone view rectangular. + +Blue clay. + +Pl. 2, Fig. 11. + +The form corresponds to the original specimens of Wm. Smith in the deposit +of Stavenger, Norway. + +The genus Cyclotella comprises about seventy specific names, many of which +may be referred to other genera, while some of Ehrenberg's are incapable of +verification on account of the small size of the figures and the lack of +sufficient description. About half of the forms are marine. The fresh-water +species are usually found living in more or less stagnant water or in pools +contaminated with drainage, being an exception to the general rule that +diatoms are more abundant in water free from deleterious matter. + + +{21}COSCINODISCUS EHR. (1838) + +(coscinon, a sieve, and discus) + +Frustules solitary, cylindrical, compressed; valve circular or elliptical; +surface flat or sometimes convex near the border; markings more or less +angular, radiating, sometimes fasciculate; border usually well defined. +Central space, if present, hyaline, sometimes surrounded with a rosette of +large cells. + +Chromatophores round, angular or irregular discs usually without pyrenoids +(Karsten). + +Rattray's classification is here followed, so far as it refers to our +species. + +_Excentrici._--Valves circular; central space absent; markings angular, in +oblique, decussating rows. + +_Lineati._--Central space absent; markings angular, oblique decussating +rows straight. + +_Fasciculati._--Markings fasciculate, or sometimes only near the border. + +_Radiati._--Markings rounded or angular, more or less radiate. + +_Elaborati._--Valves elliptical, markings rounded. + + +EXCENTRICI + +COSCINODISCUS EXCENTRICUS EHR. + +Valve with a hyaline excentric space from which proceed, usually in six +directions, rows of polygonal markings decreasing toward the narrow, +coarsely striated border, the rows appearing convex toward the centre. +Apiculi at unequal distances apart. Quite variable in size. + +Common in the blue clay and along the coast. + +Pl. 2, Figs. 14 and 20. + +Fig. 20 is probably var. _perpusilla_ Grun. (Diat. Fr. Jos. L., Pl. 4 (D), +Fig. 7). + + +LINEATI + +COSCINODISCUS LINEATUS EHR. + +Valve circular, markings hexagonal, cells in parallel rows. Border narrow, +cellular. + +Blue clay and Atlantic coast. Not common. + +Pl. 3, Fig. 8. + + +FASCICULATI + +COSCINODISCUS NITIDUS GREG. + +Valve flat, markings rounded, distant, radiate, decreasing toward the +border which is coarsely striate. Quite variable in size and in the +distance between the markings. + +Blue clay and Atlantic coast. Common. + +Pl. 2, Fig. 18. + + +COSCINODISCUS NITIDULUS GRUN. + +Valve usually not quite circular; markings smaller than in nitidus and +fasciculate near the border. + +Blue clay. + +Pl. 2, Fig. 19. + +Various intermediate forms between nitidus and nitidulus occur. + + +COSCINODISCUS SUBTILIS EHR. + +Markings polygonal, irregular at the centre, but forming numerous fasciculi +radiating {22}toward the border, the rows parallel to the central row of +each fasciculus. Border narrow with fine striae; apiculi often present +between the fasciculi. + +Blue clay and along the coast. Very common in the water supply of +Philadelphia and Camden, where the diameter seldom exceeds 40 [mu] and the +markings on the semi-radius are 10 in 10 [mu]. + +Pl. 2, Fig. 17. + + +COSCINODISCUS DENARIUS SCHMIDT + +Markings larger than in C. subtilis, equal, forming usually ten fasciculi, +each beginning near the semi-radius and containing ten parallel rows of +granules. + +Common in the blue clay and sparingly along the coast. + +Pl. 2, Fig. 13. + +Forms are found intermediate between C. subtilis and C. denarius, as shown +in Fig. 15. + + +COSCINODISCUS POLYACANTHUS GRUN. + +Markings angular, 10 in 10 [mu], decreasing toward the border, fasciculate. +Apiculi large, twelve or more, usually inserted at the middle of each +fasciculus, and extending into the interior of the cell. The apiculi in +outline resemble the heads of horse-shoe nails, and are seen with +difficulty except when the valve is examined from the inner side. Border +narrow, striated. Diam. 70 [mu]. + +Pensauken, N. J., artesian well. + +Pl. 38, Fig. 5. + +Rattray's description of _C. polyacanthus_ var. _intermedia_ Grun., from +Cape Wankarema, Siberia, gives the diam. as 60 [mu], and there are about 7 +markings by actual count in 10 [mu] in Grunow's figure (Diat. Fr. Jos. +Land, Pl. 3 (C), Fig. 25). The apiculi are more numerous, but there appears +to be little doubt of the general similarity. The Philadelphia form is +abundant in the Pensauken well deposit at a depth of 33 ft. The apiculi +become quite distinct in slides stained with silver nitrate by Mr. F. J. +Keeley; they are distinct from small apiculi sometimes evident between the +fasciculi. The specimens in the Pensauken deposit are mingled with other +forms which cannot be distinguished from _C. subtilis_. Whether the two are +identical, I am unable to determine. Rattray (Rev. Cos., p. 47) refers to +H. L. Smith's Type Slide No. 100, from rice-field mud, Savannah, Ga., as +_C. subtilis_. In Smith's slide, in my possession, a number of the forms +show faint outlines of the large apiculi and are otherwise exactly like C. +polyacanthus. + + +RADIATI + +COSCINODISCUS VELATUS EHR. + +Markings angular, decreasing slightly toward the coarsely striated border, +covered with fine puncta. + +Blue clay. + +Pl. 3, Fig. 2. + + +COSCINODISCUS MARGINATUS EHR. + +Markings rounded, large, decreasing toward the broad border, which is +coarsely marked with distant striae. The cells are punctate. + +Common in the blue clay. + +Pl. 3, Fig. 9. + +In the fossil forms the puncta are not evident, hence the species is +usually described as not punctate. + + +{23}COSCINODISCUS RADIATUS EHR. + +Markings polygonal, slightly decreasing toward the border where they are +much smaller; border well marked, striate. Quite variable in size. + +Common in the blue clay and along the coast. + +Pl. 3, Fig. 11. Fig. 1 is probably a smaller form. + + +COSCINODISCUS SUBAULACODISCOIDALIS RATTR. + +Markings small, decreasing toward the border in somewhat fasciculate rows. +About one-third the distance from the border are five (Rattray finds six) +well-marked apiculi somewhat resembling those of Aulacodiscus. Border +narrow, hyaline. + +Rare in the lower stratum of the blue clay. + +Pl. 3, Fig. 4. + + +COSCINODISCUS ARGUS EHR. + +Markings angular with central dots, increasing from the centre toward the +border, where they are smaller. + +Blue clay. + +Pl. 3, Fig. 7 (a small form). + + +COSCINODISCUS BIANGULATUS SCHMIDT + +Central space and rosette absent, markings large, angular, not punctate, +with large central papillae, decreasing toward the border. Border wide, +coarsely marked with rows of granules, and with two indentations on the +inner side distant from each other about two-thirds of the diameter. + +Blue clay. + +Pl. 3, Fig. 3. + +Distinguished from Coscinodiscus asteromphalus var. omphalantha Grun., +which also has two constrictions, by the absence of punctate markings. + + +COSCINODISCUS ASTEROMPHALUS EHR. + +Central space small, surrounded by a rosette of large polygonal cells from +which radiate hexagonal cells, increasing about half way toward the border +and then slightly decreasing. Cells punctate. + +Blue clay. + +Pl. 2, Fig. 16; Pl. 40, Fig. 12. + + +COSCINODISCUS ASTEROMPHALUS VAR. OMPHALANTHA (EHR.) GRUN. + +Central space absent, rosette evident. Markings 2-1/2 in 10 [mu], somewhat +smaller near the rosette and decreasing near the border, which is +constricted in two places, as in C. biangulatus. + +Blue clay. + +Pl. 38, Fig. 10. + + +COSCINODISCUS OCULUS-IRIDIS EHR. + +Central space and rosette distinct; markings polygonal, not punctate, with +large papillae, smaller near the rosette, increasing toward the +semi-radius, and then decreasing to the striated border which is +comparatively narrow. + +Blue clay and Atlantic coast. + +Pl. 3, Fig. 10. + + +{24}ELABORATI + +COSCINODISCUS LEWISIANUS GREV. + +Valves elliptical, major axis a little more than twice the minor. From a +point, usually near one side, radiate rows of granules in lines nearly +parallel to the major axis. Border broad, with distinct striae. + +Great Sedge Island, N. J. (artesian well), and in outcrops later than the +Miocene, where it is usually found. + +Pl. 3, Fig. 5. + + + +2. ACTINODISCEAE + +ACTINOPTYCHINAE + +Valves divided into sectors alternately elevated and depressed. + +(1) _Actinoptychus._--Sectors plane. + +(2) _Polymyxus._--Sectors convex. + + +ACTINOPTYCHUS EHR. (1839) em. V. H. (1890) + +(actis, a ray, and ptyx, a fold) + +Frustule cylindrical, less in length than the diameter, in zone view +undulated. Valve divided into six or more sectors alternately raised and +depressed, areolate and punctate, varying in the alternate divisions. The +areolation is confined to the outer layer of the valve while the punctation +is usually on an inner valve often found detached. Processes on the border, +three or more. Umbilicus circular or angular, hyaline. + + +ANALYSIS OF SPECIES + + + Sectors, six undulatus + + Sectors, eight or more, cellular heliopelta + + Sectors, fourteen, punctate vulgaris + + +ACTINOPTYCHUS UNDULATUS (KUETZ.) RALFS + +Valve areolate and punctate in quincunx, divided into six equal sectors, +alternately elevated or depressed, their areolations appearing different. +Margin well defined. Umbilicus smooth, hexagonal. Processes three, +sometimes six, inserted within the margin of each alternate division. Very +variable in size and appearance. + +This is the Actinocyclus of Bailey, figured and described in Amer. Jour. +Science, 1842, p. 93, Pl. 2, Fig. 11, but not named. Kuetzing describes and +names it and refers to Bailey. + +_Actinoptychus omphalopelta_ Ehr. + +_Actinoptychus cellulosa_ Ehr., H. L. Smith Sp. Typ., 384. + +Quite common in marine and brackish water and in the blue clay. + +Pl. 4, Figs. 1, 2, 4 and 6. + + +ACTINOPTYCHUS VULGARIS VAR. INTERRUPTA N. VAR. + +Valve with fourteen sectors, the alternate ones divided by a smooth +lanceolate space for about one-half the radius, forming with the smooth, +circular umbilicus a seven pointed star. The sectors thus divided have +coarser puncta in quincunx than the other sectors, ending in a smooth area +near the margin, and also larger black puncta scattered from the centre to +the semi-radius. + +Near A. vulgaris var. neogradensis Pant. + +Blue clay. Not common. + +Pl. 4, Fig. 5. + + +{25}ACTINOPTYCHUS HELIOPELTA GRUN. VAR.? + +Valve circular, sectors, eight, umbilicus circular, without rays; border +wide, cellular, with distinct rays. Inserted at a distance within the inner +edge of the border are large processes, one on each of four alternate +sectors, and two on each of the others. The sectors are cellulate and +punctate. + +Near A. heliopelta var. versicolor Brun., which, however, in the specimen +in my collection from Atlantic City (artesian well), has a greater number +of processes and they are situated on the edge of the border. + +Outcrop at Buckshutem, N. J. Rare. + +Pl. 4, Fig. 3. + +It has been quite well determined, I think, that the typical forms of A. +heliopelta occur at the base of the Miocene. At Rock Hall, Md., on the +eastern shore of Chesapeake Bay, at a depth of from 21 to 130 ft., and at +Wildwood, N. J., at a depth of from 78 to 179 ft., diatomaceous beds occur +considered by Mr. Lewis Woolman (Geol. Surv. of N. J., 1898, pp. 116-121) +"as synchronous in age," the former being deposited in the Delaware River +Delta and the latter in the Chesapeake in post-miocene times. In each of +these beds a small form of A. heliopelta is rarely found. The material at +Buckshutem is post-miocene, and the form here figured shows a marked +variation from the Miocene species and a gradual approach toward A. +undulatus. + + +POLYMYXUS L. W. BAIL. (1855) + +Valve circular, usually divided into fourteen sectors which are on the same +plane at the centre, but the alternate ones are elevated into mammillated +projections terminated by small processes on the margin. Zone view +rectangular with undulations subconical, terminated by the processes. + + +POLYMYXUS CORONALIS L. W. BAIL. + +Central space hyaline, rounded or slightly stellate, from which radiate +rows of fine puncta in quincunx, shown in the figure only on the alternate +elevations, the depressed interspaces being out of focus. The mammillae are +stated by Bailey to vary from six to ten. + +Very rare in the blue clay (Walnut St. Bridge). Occurs also in the Wildwood +deposit (Bull. Torrey Bot. Club, 1895, p. 261). + +Pl. 4, Fig. 7, and Pl. 5, Fig. 2. + + + +3. EUPODISCEAE + +_Aulacodiscinae._--Valves with mammiform elevations near the border +surmounted by nipple-like processes. + + +AULACODISCUS--THE ONLY GENUS AS ABOVE + +_Eupodiscinae._--Valves with ocelli. + +(1) _Actinocyclus._--Valve with one small ocellus; striae radial. + +(2) _Eupodiscus._--Valve with one or more ocelli; striae not radial. + +(3) _Auliscus._--Valve with large, elevated ocelli. Central area hyaline. +Markings granular and costate. + +(4) _Pseudauliscus._--Valve with radiating granules. No central space. + + +{26}AULACODISCUS EHR. (1844) em. RATTR. (1888) + +(aulax, a furrow, and discus) + +Valve usually circular, plane or with an elevated zone, frequently inflated +beneath the processes; central space irregular or rounded, sometimes +absent; markings granular, radial, sometimes in a reticulum. + +The genus comprises more than one hundred species most of which are fossil, +and is represented in this locality by a single form, _A. argus_, included +by Rattray in his section "Retiformes," distinguished by the presence of a +reticulum. + + +AULACODISCUS ARGUS (EHR.) SCHMIDT + +Frustule in zone view elliptical. Valve circular, 125-190 [mu] in diam., +closely covered with two kinds of markings, one, a mesh of large, +radiating, angular cells, the outer plate, and the other, radiating rows of +circular granules with hyaline spaces intervening and closer near the +border, forming the inner plate which can occasionally be seen detached. +Central space absent. The walls of the angular cells are crossed with fine +lines and are probably composed of granules compressed so closely as to +produce partial opacity, the depth of which depends in a measure not only +on the superposition of the two plates, but on the relative closeness and +thickness of the cell-walls. In a fully-developed specimen the effect is to +produce more or less triangular cells containing three or four granules. In +some cases the opacity is so great as to render detail invisible. + +In the figure the valve is supposed to be divided into three sectors, +illustrating at "a" the lower plate, at "c" the combination of the upper +and lower plates, and in the other sector the cellular mesh of the upper +plate. Processes, usually three, quite robust and inserted at from +one-fourth to one-fifth the length of the radius from the border which is +striated on the inner side. A form with four processes is found in the +lower blue clay. + +_Tripodiscus argus_ Ehr. + +_Eupodiscus argus_ (Ehr.) Wm. Sm. + +Not uncommon in the blue clay. + +Pl. 4, Fig. 8. + + +ACTINOCYCLUS EHR. (1837) + +(actis, a ray, and cyclos) + +Valve circular or elliptical; surface flat at the centre, sloping toward +the border. Central space usually evident, rounded or irregular. Markings +rounded, granular, punctiform, in radial, or nearly radial, rows, sometimes +fasciculate. A nodule, more or less evident, is found near the border which +is usually striate. + +Chromatophores round discs or granules. + + +ANALYSIS OF SPECIES + + + Valve circular, rows radial, hyaline lines at the border barkleyi + + Valve circular, rows fasciculate moniliformis + + Valve elliptical ellipticus + +The nodule is generally supposed to be a thickening of the cell-wall, and, +in the opinion of Rattray, a projection outward, but "whether there may not +be at the same time a slight inward protuberance is difficult to +determine," though, as a rule, he seems to "think there is not." + + +{27}ACTINOCYCLUS BARKLEYI VAR. AGGREGATA RATTR. + +Surface flat from centre to semi-radius. Central space irregular, sometimes +with a few scattered granules. Markings round with central dots distinct, +about 7 at the centre, decreasing in straight radial rows to 12 in 10 [mu] +at the border, where they form moniliform striae. Border narrow with striae +about 16 in 10 [mu]. Hyaline interspaces at the origin of the shorter rows, +but not at equal intervals. At the border, linear hyaline spaces occur at +somewhat irregular intervals between the moniliform striae owing to the +termination of certain radial rows before they reach the circumference. +Nodule small, from one-seventh to one-fourth the radius from the border. + +According to Rattray the distinction between A. ralfsii and A. barkleyi is +partly in the absence of the zone arrangement of the hyaline spaces in the +latter, and to the slight differences in the number of granules. The +variety aggregata differs from the type form of barkleyi mainly in the +distance of the nodule from the border. I have specimens from the blue clay +material at Walnut St. Bridge, and from Smith's Island, in which the +distance from the border in one case is, as stated above, quite different +from that in the other. In specimens from Morris Cove, Conn., the locality +referred to by Rattray, variations occur. + +Blue clay. + +Pl. 6, Fig. 1. + +In the figure the subulate hyaline spaces at the border are, in some +instances, wider than usual. + + +ACTINOCYCLUS MONILIFORMIS RALFS + +Surface flat, from centre to about five-sixths of the radius. Central space +rounded, with one or more granules. Markings, 8 in 10 [mu], round, in +radial rows, fasciculate, the oblique transverse rows irregular, very +slightly decreasing until near the edge of the flattened zone, and then +suddenly decreasing and appearing as decussating lines oblique to the +border. Apiculi distinct, interfasciculate within the border. Nodule quite +evident, surrounded by a rather wide irregular hyaline space on the margin +of the flattened zone in the middle of the fasciculus. Border wide, with +striae about 20 in 10 [mu]. + +Blue clay. Port Penn. Not common. + +Pl. 6, Fig. 2. + +Equivalent to Actinocyclus ehrenbergii, H. L. S. Type Slide 10. + +In a valve from Port Penn, Delaware Bay, two nodules occur nearly opposite +each other. + + +ACTINOCYCLUS ELLIPTICUS VAR. DELAWARENSIS N. VAR. + +Valve rhombic-elliptical. Markings somewhat angular, 6 in 10 [mu] at the +centre where they are sub-concentric, thence decreasing in lines radiating +more or less toward the border, where they suddenly become punctiform, +striae about 20 in 10 [mu]. Border equal to one-fifth the radius. A nodule +is found on the inner side of the border. Apiculi apparently absent. + +The markings are larger than in the Richmond forms which are associated by +Rattray with Actinocyclus ellipticus Grun. The form corresponds closely to +Witt's Cestodiscus ovalis var.? (Witt, Polierschief. von +Archangelsk-Kurojedowo, Pl. 8, Fig. 2), except as to the border. It does +not answer to Van Heurck's figure or any other. + +Blue clay. Very rare. + +Pl. 3, Fig. 6. + + +{28}EUPODISCUS EHR. (1844) + +(eu, well, pous, a foot, and discus) + +Valve circular, 45-117 [mu] in diam. (De Toni). Central space absent, +surface plane with angular cells. At the border short, circular processes +or ocelli. + + +EUPODISCUS RADIATUS BAIL. + +Valve with radiating hexagonal cells, sometimes slightly curved toward the +large ocelli inserted near the border which are hyaline at the centre. +Border wide, coarsely striate. + +The number of ocelli heretofore recorded is four. Specimens with five +processes are found in the artesian well at St. Augustine, Fla., and in +material at Twelfth and Brandywine Sts. Mr. Hugo Bilgram has discovered +valves with three and six ocelli. + +Not common in the blue clay, but abundant along the southern coast of the +Atlantic states and the Gulf of Mexico. + +Not Eupodiscus radiatus Wm. Sm, which is Biddulphia smithii (Ralfs) V. H. + +Pl. 5, Fig. 3. + + +AULISCUS EHR. (1843) + +(aulax, a furrow, referring to the grooves in certain species, according to +De Toni, but preferably from auliscos, a small reed, referring to the +processes?) + +Frustule cylindrical; zone with longitudinal rows of fine puncta. Valve +circular or elliptical, plane except near the processes; central area +hyaline, usually circular. Markings of two kinds, granules radiating or +scattered and radiating, costate lines, prominent or indistinct. Processes, +two or three, large, short, cylindrical, with hyaline surface, near the +ends of the major axis in a line oblique to it. + +Auliscus is divided by Rattray into fourteen sections, defined chiefly by +the character and arrangement of the markings. About eighty species are +described, but as many of the forms are fossil, occuring in the Miocene of +California, Oamaru and elsewhere, and as so few species are found in this +locality, I shall refer but briefly to this division. + + + _Striolati._--No transverse median areas, striae + inconspicuous punctatus + + _Lineolati._--Markings distinct, pruinose, interrupted pruinosus + + _Costati._--Transverse median areas usually distinct, sculptus + markings continuous, costate caelatus + +AULISCUS PUNCTATUS BAIL. + +Valve broadly elliptical, or suborbicular, covered with delicate +interrupted striae radiating in sinuous lines to the circumference, more +evident on the transverse median area; puncta 3 in 10 [mu], grouped into a +rounded area on each side of the median line, elsewhere scattered. Central +space rounded, processes two, large, suborbicular. + +Port Penn, Delaware River. Rare. + +Pl. 5, Fig. 6. + + +AULISCUS PRUINOSUS BAIL. + +Valve elliptical, with distinct, interrupted, pruinose, irregular markings +diverging in curved lines toward the circumference in the median part and +converging toward the processes, interspersed with numerous darker markings +having the appearance of apiculi. Central space nearly circular, sometimes +with several granules. Processes large near the ends of the major axis and +not oblique to it, or scarcely so, the edges with a crenulate border. + +Blue clay. Rather rare. + +Pl. 5, Fig. 8. + + +{29}AULISCUS SCULPTUS (WM. SM.) RALFS + +Valve elliptical or subcircular, median areas distinct, rounded, +circumscribed by coarse distant costae radiating near the border where they +are more evident, and converging toward the processes. Central space +rounded, sometimes indefinite. Processes, two, circular. + +Typical specimens show wide, coarse, distant costae, but, in some cases, +the median areas are indistinctly outlined. + +Blue clay. + +Pl. 5, Fig. 5. + + +AULISCUS CAELATUS BAIL. + +Valve elliptical or subcircular, with radiating costae, more evident around +the median areas and at the border, converging toward the processes, with +intermediate punctate radiating lines. Central space rounded or irregular. +Processes circular. + +A. sculptus has coarser costae and the interspaces are hyaline, or +apparently so, while in A. caelatus the punctate striae between the costae +are more evident. + +Blue clay. Not uncommon. + +Pl. 5, Fig. 4. + +Fig. 7 is a small, indefinite form intermediate between A. sculptus and A. +caelatus. The numerous variations in this genus make it difficult to +satisfactorily differentiate the species. The size of the four above +described varies from 40 to 150 [mu]. + + +PSEUDAULISCUS A. S. (1875) AND LEUDUGER-FORTMOREL (1879) + +Valve circular or subcircular, nearly flat or depressed at the centre. +Central space not evident. Processes circular, with narrow border, near the +circumference. Border narrow, striated. Markings granular, radiating, +sometimes interspersed with striae and apiculi. + +Differs from Auliscus chiefly in the absence of a central space and costae. + + +PSEUDAULISCUS RADIATUS (BAIL.) RATTR. + +Valve circular, or nearly so, flat. Central area with scattered granules +radiating and increasing in size outward in diverging rows toward the +border which is coarsely striated. Processes, two, circular. Two small +apiculi are inserted at about one-fifth the radius from the border near the +ends of the minor axis. + +Blue clay. Rare. + +Pl. 5, Fig. 9. + +The apiculi are not always figured. They appear in a number of specimens +from the Miocene of Maryland, Atlantic City, Harvey Cedars and Newbern. + + +PSEUDAULISCUS SPINOSUS (CHRISTIAN) RATTR. + +Valve subcircular or slightly quadrangular, depressed at the centre and +rising to an elevated zone near the border, the two zones separated by a +distinct line. The inner zone indistinctly reticulate with fine puncta +radiating from the centre and apiculi at intervals. The outer zone with +smaller apiculi surrounding the inner zone and with intermingled rows of +fine puncta and interrupted diverging striae. Near each end of the minor +axis is a rather long, robust spine inserted at one-fourth the radius from +the border which is narrow and striated. Processes circular, close to the +circumference. + +_Auliscus spinosus_ Christian. + +Blue clay. Rare. + +Pl. 5, Fig. 10. + +The genus is named by Schmidt, described by Leuduger-Fortmorel and +emendated by Rattray. + + + +{30}BIDDULPHIOIDEAE + +BIDDULPHIEAE + +(_a_) _Triceratiinae._--Frustule cylindrical or prismatic, with three or +more sides. + +(_b_) _Biddulphiinae._--Frustule cylindroid; valve with ends elevated into +round processes or long horns. + +(_c_) _Anauleae._--Valve elliptical, lunate or triangular, with internal +septa. + +(_d_) _Euodieae._--Frustule cuneate in zone view; valve lunate. + + + +(_a_) TRICERATIINAE + +(1) _Ditylum._--Frustule imperfectly siliceous. Zone with numerous +divisions. Valve with central spine. + +(2) _Trinacria._--Processes with sharp spines. + + +DITYLUM BAIL. (1861) + +(dis, two, and tyle, a swelling, referring to the outline of the frustule) + +Frustule quadrangular, convex at the ends. Valve triangular, with +undulating sides, the angles ending in a sharp point surmounted by a +bristle. Surface of valve convex at centre from which projects a long stout +spine. + + +DITYLUM INTRICATUM (WEST) GRUN. + +Valve with the angles separated from the central part by lines imitating +septa. Surface with radiating lines of fine puncta. + +Blue clay. Rare. + +Pl. 6, Fig. 4. + +Detached valves only have been found in the blue clay. The form is regarded +as but slightly siliceous and, therefore, the zone or girdle not being +found in the fossil deposits, I am unable to illustrate it from material in +the vicinity. On Plate 38, Figs. 6 and 7, I have sketched the zone and +valve views of specimens found recently at Vera Cruz and labelled by H. L. +Smith Triceratum intricatum West. I can find no difference between the +recent and fossil forms of the valves. The zone is covered with fine puncta +in quincunx, not visible under ordinary illumination. + +The form as figured in Plate 6 corresponds to the figure of Lithodesmium +undulatum Ehr. in Van Heurck, and West, in describing the Triceratium +undulatum Wm. Sm. (figured as T. striolatum), thought that his T. +intricatum was distinct from Ehrenberg's form on the ground that the latter +came from the "Bermuda" (Nottingham) earth and must be strongly siliceous. +Lithodesmium is characterized by the envelopment of the frustules by a +cellular membrane which does not appear, evidently, in Ditylum. D. +brightwellii is distinguished by its crown of spines on the margin; +otherwise it closely resembles D. intricatum. + + +TRINACRIA HEIB. (1863) + +(treis, three, and acra, a point) + +Valve triangular, angles elevated into spines. Cells at the margin large. + + +TRINACRIA PILEOLUS (EHR.) GRUN. + +Valve with concave sides. Surface concave with unequal punctiform and +scattered markings with central dots. Cells at the margin large, rounded. +At the angles, which vary in elevation, a few puncta are seen. + +_Triceratium pileolus_ Ehr. + +Blue clay. Rare. + +Pl. 6, Fig. 9. + + + +{31}(_b_) BIDDULPHIINAE + +BIDDULPHIA GRAY (1831) em. VAN HEURCK (1885) + +(a genus, constituted from Conferva biddulphiana of the English Botany, +named after a Miss Biddulph) + +Frustule prismatic or subcylindrical, concatenate, filamentous, or in +zig-zag, or, as usually found, free. Zone well developed. Valve triangular, +polygonal, elliptic or subcircular, convex, more or less elevated at the +angles into processes or horns. Markings cellular or punctate. +Chromatophores, small plates of various forms. + + +KEY TO THE SPECIES + + + Valves costate biddulphiana + + Valves not costate: + + Markings cellular, angles elevated into horns favus + + angles not elevated antediluviana + + Markings punctate, angles with subconical processes and + long spines granulata + + spines short rhombus + + spines minute smithii + + processes truncate, valve elliptical turgida + + valve orbicular laevis + + processes absent, valve divided by irregular lines alternans + + not so divided reticulum + + +BIDDULPHIA BIDDULPHIANA (SMITH) + +Frustule quadrangular with convex ends and rounded angles. Valve elliptical +with undulated sides, divided by septa into three or more sections. +Processes large, rounded, globular or subconical. Zone varying in width. +Surface with rounded reticulations in longitudinal and transverse rows, +except at the centre where they are concentric and smaller. + +_Conferva biddulphiana_ Smith (English Botany, 1807, Pl. 1762, upper +figures). + +_Diatoma biddulphianum_ Ag. + +_Biddulphia pulchella_ Gray. + +Blue clay. Hoboken Tunnel. Along the coast. + +Pl. 7, Figs. 1, 2, 3, and 4. + +Quite variable in size and number of septate divisions. Fig. 3 is an +unusual form with narrow zone, having but one row of large reticulations, +evidently a young frustule. + + +BIDDULPHIA FAVUS (EHR.) V. H. + +Frustule quadrangular, elevated at the angles into subconical processes +oblique to the longitudinal axis. Valve triangular or quadrangular, plane, +of two layers, the outer layer composed of large hexagonal cells in rows +parallel to the sides, the inner of small puncta radiating from the centre. +Zone punctate in quincunx, never found open. + +_Triceratium favus_ Ehr. + +Blue clay. Common along the coast. + +The quadrangular form occurs only southward. + +Pl. 6, Fig. 6. At "a" a cell showing the lower punctate layer. Pl. 40, Fig. +16, a transverse section of a portion of the valve showing the cellular +structure and the punctated lower stratum. + + +{32}BIDDULPHIA ANTEDILUVIANA (EHR.) V. H. + +Frustules quadrangular, sometimes united in zig-zag chains. Valve +quadrangular with more or less concave sides, sometimes cruciform. Surface +with angular cells arranged in concentric and radiating lines increasing +toward the circumference. At each angle is a large, rounded process, which, +as well as the secondary layer, scarcely visible, is finely punctate. + +_Amphitetras antediluviana_ Ehr. + +_Amphitetras tessellata_ Shad. + +Blue clay. Rare. + +Pl. 6, Fig. 3. + +A cruciform variety occurs at Pensauken, N. J., artesian well (Coll. F. J. +Keeley). + + +BIDDULPHIA GRANULATA ROPER + +Valve elliptical-lanceolate, convex, with diagonal rows of puncta 12 in 10 +[mu] and sometimes with small scattered spurs. Processes inflated at the +base, obtuse at the ends, which are curved outward toward alternate sides. +Near each process and on opposite sides of the longitudinal axis is placed +a stout spine bent or curved inward near the middle. Connective zone with +diagonal rows of puncta smaller than those on the valve. + +Pavonia, N. J., artesian well. Fossil in the Pleistocene. Along the coast. +Not common. + +Pl. 7, Fig. 6. + + +BIDDULPHIA RHOMBUS (EHR.) WM. SM. + +Valve rhomboidal, sometimes triangular, with subconical processes. Surface +convex with hexagonal reticulations, 7-9 in 10 [mu], irregular at the +centre and radiating to the circumference. Minute spurs are scattered over +the surface, and on each side are usually two or three short spines. + +Common along the coast and fossil in the Miocene and later deposits. + +Pl. 7, Fig. 5 (somewhat inclined, as usually seen). + + +BIDDULPHIA SMITHII (RALFS) V. H. + +Valve orbicular, convex, with reticulations 5 in 10 [mu] radiating from the +centre and decreasing toward the margin and processes which are truncate. A +short spine is found on each side half way between the processes. Zone +narrow with fine puncta 12 in 10 [mu] in longitudinal rows. + +_Cerataulus smithii_ Ralfs. + +_Eupodiscus radiatus_ Wm. Sm. + +Blue clay. Along the coast southward. + +Pl. 7, Fig. 8. + + +BIDDULPHIA TURGIDA (EHR.) WM. SM. + +Valve elliptical or orbicular, surface convex. Processes very large, +cylindrical, placed obliquely and inclined by the torsion of the frustule. +Between the processes are two stout spines, one on each side, frequently +forked at the ends. Puncta fine, irregular at the centre and radiating +toward the circumference. + +_Cerataulus turgidus_ Ehr. + +Blue clay. Along the coast. Quite variable in size. + +Pl. 7, Fig. 7. + + +{33}BIDDULPHIA LAEVIS EHR. + +Valve suborbicular or triangular, with short, truncate processes. Surface +with fine puncta about 13 in 10 [mu] radiating in straight or curved lines +toward the circumference and with fine spurs at intervals. Nearer one +process than the other, and about half way between centre and +circumference, are two small spines, one on each side. Quite variable in +size. + +Blue clay. Common along the coast. + +Pl. 7, Fig. 9. + +Fig. 10 (magnification about 260 diameters only) illustrates sporangial +frustules discovered by Mr. T. Chalkley Palmer at Reedy Island, Delaware +River. In frustules having a cylindrical form, the endochrome lines the +cell-walls in the form of granules which become congregated toward the +centre in the sporangia. + + +BIDDULPHIA ALTERNANS (BAIL.) V. H. + +Valve triangular or, rarely, quadrangular, with sides straight or slightly +concave, usually unequal. Angles obtuse, separated from the centre by +costate lines. Surface with puncta of irregular shape, large at the centre, +with smaller puncta interspersed. In many valves several lines appearing +like costae extend inward from the border in various directions. Angles +with small puncta in transverse and longitudinal rows. + +_Triceratium alternans_ Bail. + +Blue clay. Along the coast. + +Pl. 6, Fig. 7 and probably Fig. 8. + + +BIDDULPHIA RETICULUM (EHR.) + +Frustule quadrangular. Valve triangular with straight or concave sides and +rounded angles. Surface convex at the centre and angles. Markings of +unequal size, mostly larger at the centre, scattered; at the angles, small +puncta in longitudinal rows. + +_Triceratium sculptum_ Shad. + +_Triceratium punctatum_ Br. + +_Triceratium obtusum_ Br. + +For explanation of the synonymy see "Biddulphoid Forms of N. A. Diat.," +Proc. Acad. Nat. Sci., 1900, p. 724. + +Blue clay. Along the coast. + +Pl. 6, Fig. 5. + + + +(_c_) ANAULEAE + +EUNOTOGRAMMA WEISSE (1854) + +(eu, well, noton, a back, and gramma) + +Frustule quadrangular. Valve elliptical or lunate divided by septa which +constrict the margin. Surface flat with punctate markings. + + +EUNOTOGRAMMA LAEVE GRUN. + +Valve lunate with obtuse ends. Septa, from four to eleven or more. Surface +with puncta in transverse and longitudinal rows, sometimes indistinct and +scattered. + +Shark River. Rare. More common southward. Fossil at Buckshutem, N. J. + +Pl. 7, Fig. 11, and Pl. 10, Fig. 15. + +I am unable to distinguish between E. laeve and E. debile, as intermediate +forms occur. + + +{34}TERPSINOE EHR. + +(terpsinoos, gladdening?) + +Frustules quadrangular, adnate in filaments, usually free. Valve elliptical +or triangular, with undulating sides divided by septa into three or more +sections. + + +TERPSINOE AMERICANA (BAIL.) RALFS + +Valve lobed at each end or angle. Central space rounded, hyaline. Surface +with fine puncta in radiating lines. + +Blue clay. Not common. + +Pl. 6, Fig. 10. + + +TERPSINOE NOVAE-CAESAREAE BOYER + +Valve triangular, with concave sides and broad angles equally three-lobed, +separated from the central part by septa. Central space small or absent. +Puncta delicate, radiating or scattered. L. of side 62 [mu]. + +Pleistocene clay at Buckshutem, N. J. Fossil at Wildwood, N. J. + +T. americana, forma trigona Pant.? (Le Diatomiste, Vol. 2, p. 207.) + +Pl. 6, Fig. 11. + + + +(_d_) EUODIEAE + +EUODIA BAIL. (1860) + +(derivation uncertain; apparently from euodia, fragrant, probably a +euphemism) + +Frustule in zone view cuneate. Valve semi-lunate, coscinodiscoid. + + +EUODIA GIBBA BAIL. + +Valve with rounded markings, larger and scattered at the centre, radiating +at the circumference and in indefinite straight rows at the semi-radius. + +Delaware Bay (Mann). + +Pl. 5, Fig. 1. + +I have not seen this in the Philadelphia material. The figure is drawn from +a specimen from the Gulf Stream, S. Atlantic. + + + +{35}PENNATAE + +Valve zygomorphous. Structure pinnate, not concentric. Valve divided either +by a true raphe or cleft or by a linear space or line imitating a raphe. + +Divided into three Groups: + +1. _Fragilarioideae._--Valves without a raphe; usually with a pseudoraphe +or median line. + +2. _Naviculoideae._--Either one or both valves with a true raphe. + +3. _Surirelloideae._--Valves in which the raphe is concealed near the +margin on one or both sides of each valve in a more or less elevated keel +or wing. + + + +FRAGILARIOIDEAE + +(_a_) _Tabellarieae._--Valve symmetrical with respect to both the +longitudinal and transverse axes; septate, not cuneate. + +(_b_) _Meridioneae._--Valve symmetrical with respect to the longitudinal +axis, asymmetrical to the transverse axis, cuneate, finely striated. + +(_c_) _Fragilarieae._--Valve of varied shape, not cuneate; costate or with +transverse rows of puncta. + + + +(_a_) TABELLARIEAE + +Frustule in zone view rectangular, in valve view linear or +linear-elliptical, sometimes constricted in the middle, symmetrical to both +axes, not cuneate; with two or more septa or annuli. + +Chromatophores numerous, granular. + +_Rhabdonema._--Frustules with numerous septate partitions having one or +several foramina. Transverse costae or rows of coarse puncta. + +_Tabellaria._--Frustules with two to six nearly straight septa. Transverse +striae subtly punctate. + +_Grammatophora._--Frustules with two sinuate perforate curved septa. +Transverse striae subtly punctate. + +_Striatella._--Frustules with alternate partitions, septate or partly so. + +_Attheya._--Frustules not septate but with numerous annuli. + + +RHABDONEMA KUETZ. (1844) + +(rhabdos, a rod, and nema, a thread) + +Frustules quadrangular, concatenate, composed of numerous septate +partitions with transverse costae or rows of puncta. Valves elliptical, +with a pseudoraphe and transverse apparent costae and punctate lines; the +partitions with one or several foramina. + +Chromatophores in rosettes of various kinds (Karsten); usually parallel to +the septa. + + +RHABDONEMA ARCUATUM (LYNG.) KUETZ. + +Valve hyaline at the ends, with transverse rows of puncta producing the +appearance of costae between the rows; pseudoraphe distinct; foramen +single. + +_Diatoma arcuatum_ Lyngbye. + +Common along the coast. + +Pl. 8, Figs. 1, 2, and 3; Pl. 40, Fig. 10. + +{36}According to T. H. Buffham (Jour. Quek. M. C., Series 2, Vol. 2, p. +131), the frustules are of two kinds, those in which the length and breadth +are the same and those which are much lengthened, with a wide hyaline +girdle frequently in the middle. At the time of fructification the smaller +frustules are attached to a larger one which produces a sporangium at the +end of the girdle from which the other end of the frustule has disappeared, +or, if the two halves of the frustule remain, two sporangia are formed. + + +RHABDONEMA MINUTUM KUETZ. + +Frustules small; valve not smooth at the ends, elliptical or +lanceolate-elliptical, with transverse rows of puncta; pseudoraphe +distinct. Foramen single, alternating above and below in adjoining +partitions. + +Common in the blue clay and along the coast. + +Pl. 8, Fig. 7 and Pl. 38, Fig. 11. + + +RHABDONEMA ADRIATICUM KUETZ. + +Valve linear-lanceolate, with smooth angles; rows of puncta transverse, the +intervals appearing as costae, as in arcuatum. Foramina, three. + +Blue clay in the Pensauken and Pavonia deposits and along the coast. + +Pl. 8, Figs. 4, 5 and 6. + + +TABELLARIA EHR. (1839) + +(tabella, a tablet) + +Frustules quadrangular, adnate in filaments, frequently found in zig-zag +chains, united by a gelatinous isthmus, at length separating. Valve linear, +inflated in the middle and at the ends; striae transverse. + +Chromatophores numerous, small, along the zones. + + +TABELLARIA FENESTRATA (LYNG.) KUETZ. + +Valve elongated; pseudoraphe narrow; transverse striae faint. In the zone +view a straight septum is shown at each end of a valve. + +Common, especially in the cedar swamps and ponds of the Pine Barren region, +N. J. + +Pl. 8, Figs. 11 and 12. + + +TABELLARIA FLOCCULOSA (ROTH) KUETZ. + +Valve linear, with median inflation larger than the terminal; pseudoraphe +rather broad in the middle; transverse striae subtly punctate. In zone view +the frustules are quadrangular, or nearly so, with about six sometimes +curved septa at one end alternating with those on the other end. + +_Conferva flocculosa_ Roth. + +Common especially in the Pine Barrens of New Jersey. + +Pl. 8, Figs. 8, 9 and 10. + + +GRAMMATOPHORA EHR. (1840) + +(from gramma, a letter, and phoreo, I bear) + +Frustules quadrangular, adnate, in zig-zag, united by an isthmus, or, +usually, found free; divided by two sinuate and perforate curved septa. +Valve linear or oblong, sometimes with sinuate sides, and with a +pseudoraphe and transverse punctate lines. + +Chromatophores granular. + + +{37}GRAMMATOPHORA MARINA (LYNG.) KUETZ. + +Valve linear-elliptical, with smooth apices. Septum with a wide undulation +near its origin, thence straight and incrassate at the end. Striae in +quincunx, 18-21 in 10 [mu]. + +_Diatoma marinum_ Lyngbye. + +Blue clay. Along the coast. + +Pl. 8, Figs. 17 and 18. + + +GRAMMATOPHORA MARINA VAR. SUBTILISSIMA (BAIL.) V. H. + +Valve linear, slightly constricted near the smooth apices. Septum undulated +near its origin and then straight, incrassate at the end. Puncta in +quincunx very subtle, 34-36 in 10 [mu]. + +_Grammatophora subtilissima_ Bail. + +Grammatophora oceanica var. subtilissima (Bail.) V. H., according to De +Toni. G. marina and G. oceanica are united by some authors; the latter has +more subtle striae. + +Along the coast. + +Pl. 8, Figs. 13 and 14. + + +GRAMMATOPHORA SERPENTINA RALFS + +Valve linear-elliptical, long, measuring to 150 [mu] (De Toni); smooth at +the apices. Septum with numerous undulations and hooked at the apex. Puncta +in quincunx, 17 in 10 [mu]. + +Along the coast. + +Pl. 8, Fig. 21. + + +GRAMMATOPHORA ANGULOSA VAR. HAMULIFERA (KUETZ.) GRUN. + +Frustule nearly quadrate; valve with rounded but not smooth apices. Septum +bent into a sharp angle near its origin and ending in a broad hook. Puncta +in transverse rows, 14 in 10 [mu]. + +Along the coast. + +Pl. 8, Figs. 15 and 16. + + +GRAMMATOPHORA ISLANDICA EHR. + +Frustule oblong; valve elliptical-lanceolate. Septum robust with several +undulations and hooked at the end. Pseudoraphe distinct; transverse rows of +puncta, 10 in 10 [mu]. + +Reported by Kuetzing in the Atlantic Ocean and by Kain at Belmar, N. J. I +have not found it on our coast and I believe, in some cases, it has been +confused with _G. angulosa_ var. _hamulifera_. The figure is drawn from an +Iceland form in H. L. Smith T. S., 186. + +Pl. 8, Figs. 19 and 20. + + +STRIATELLA AG. (1832) + +(dim. of stria, referring to the lines on the frustule) + +Frustules tabulate, adnate in short, stipitate filaments, scarcely +siliceous, divided into partitions, septate or partly so at alternate ends. + + +{38}STRIATELLA UNIPUNCTATA (LYNG.) AG. + +Frustules with numerous bent septa extending the entire length. Valve +lanceolate, somewhat unsymmetrical, subtly punctate, with pseudoraphe quite +distinct. + +"The specific name is derived from the appearance of the endochrome which +in the living specimen is invariably collected in a central mass with +slender threads radiating in all directions toward the cell-wall" (Wm. +Sm.). Pyrenoids cuneate, in the centre of the endochrome, numerous. + +Long Island Sound and along the coast. + +Pl. 8, Figs. 22 and 23. + + +STRIATELLA INTERRUPTA (EHR.) HEIB. + +Frustules quadrangular, with robust alternate septa extending to the +middle. Puncta in quincunx, 22 in 10 [mu]. + +_Tessella interrupta_ Ehr. + +Very rare along the coast. + +Pl. 8, Fig. 24. (From a form found at Stonington, Conn.) + + +ATTHEYA WEST (1860) + +(named after Thomas Atthey) + +Frustules quadrangular, tabulate, with numerous annuli. Valve +elliptical-lanceolate, with a pseudoraphe and a central punctum. Extending +from each end is a strong spine half as long as the valve. + + +ATTHEYA DECORA WEST + +The only species. Diagnosis of the genus. The valves are imperfectly +siliceous, scarcely visible in balsam. + +Very local. Abundant at Shark River, N. J. + +Pl. 8, Fig. 25. + + + +(_b_) MERIDIONEAE + +Valve symmetrical in zone and valve view along the sagittal line, but +asymmetrical to the transverse axis, cuneate. In zone view sometimes with +wedge-shaped septa. Valve finely striated, without central and usually +without terminal nodules; a pseudoraphe present. + +_Licmophora._--Frustules cuneate in stipitate fan-shaped fascicles. + +_Meridion._--Frustules cuneate in spiral fascicles. + + +LICMOPHORA AG. (1827) + +(licmos, a fan, and phoreo, I bear) + +Frustules wedge-shaped, joined together into fan-shaped, stipitate +fascicles. Valve cuneate, rounded at both ends, septate. Chromatophores +granular, round or oval in our species. + + +{39}ANALYSIS OF SPECIES + +(In accordance, so far as it relates to our species, with the +classification of C. Mereschkowsky, Diagnoses of New Licmophorae, Nuova +Notarisia, 1901.) + + + Placatae--valve narrow, striae very fine, septa superficial flabellata + + Dubiae--valve bacilliform, septa shallow, frustule with + thick walls ovulum + + Paradoxae--valve with lower end produced, striae fine, paradoxa + pseudoraphe distinct, septa deep gracilis + tincta + baileyi ? + + Lyngbyeae--valve narrow, attenuated at both ends, distinct, + septa deep lyngbyei + + Peristriatae--valve broad, pseudoraphe wide, striae robust ehrenbergii + + +LICMOPHORA FLABELLATA (CARM.) AG. + +Frustule elongate, narrow; valve narrow, lanceolate-cuneate, enlarged at +the base; striae very fine, 30 in 10 [mu]. + +_Echinella flabellata_ Carm. + +_Licmophora splendida_ Wm. Sm. + +Common along the coast. + +Pl. 9, Figs. 1 and 2. + + +LICMOPHORA OVULUM MER. + +Valve ovate, attenuated to the rounded inferior apex; pseudoraphe +indistinct, striae fine, 24 in 10 [mu]. Zone view broad, cuneate, angles +rounded, inferior apex broad; frustule robust, septa superficial, straight. +(Mereschkowsky, in part.) + +Atlantic City. Common. + +Pl. 9, Figs. 8 and 9. + + +LICMOPHORA PARADOXA (LYNG.) AG. + +Frustule broad, with rounded angles; septa curved; valve ovate, inferior +apex produced. Pseudoraphe distinct; striae varying from 25 below to 30 +above in 10 [mu]. + +_Echinella paradoxa_ Lyng. + +_Rhipidophora paradoxa_ Kuetz. + +Along the coast. + +Pl. 9, Figs. 6 and 7. + + +LICMOPHORA GRACILIS (EHR.) GRUN. + +Frustule cuneate, narrow, with sinuate margin; valve clavate, linear at the +base; striae, 20 to 22 in 10 [mu]. + +New Rochelle. Along the coast. + +Pl. 9, Fig. 11. + + +LICMOPHORA GRACILIS VAR. ELONGATA (KUETZ.) DE TONI + +As in the type, but more graceful and with deeper septa. + +_Rhipidophora elongata_ Kuetz. + +Along the coast. Not common. + +Pl. 9, Figs. 12 and 13. + + +{40}LICMOPHORA TINCTA (AG.) GRUN. + +Frustules cuneate, narrow, usually found in twos. Valve clavate, hyaline, +rather broad at the base; septa moderately deep; pseudoraphe indistinct; +striae, 27 at the base, 30 in the middle and 33 at the apex in 10 [mu]. + +_Gomphonema tinctum_ Ag. + +Along the coast. Abundant from about the middle of July to the middle of +August. + +Pl. 9, Figs. 14 and 15. + + +LICMOPHORA BAILEYI (EDW.) GRUN. + +Frustule broadly cuneate or with convex margins, rarely almost orbicular; +valve spatulate or ovate with slender, produced base; septa very deep; +pseudoraphe distinct; striae 20 in 10 [mu]. + +_Podosphenia baileyi_ (Edw.) Lewis. + +Long Island Sound and upper coast of New Jersey. + +This form is placed in a doubtful position by Mereschkowsky. As it +corresponds more closely to the Paradoxae, it is placed here provisionally. +The girdle face and apex of the valve are round, the pseudoraphe is +distinct and the septa deep, but the stipe is short. + +Pl. 9, Fig. 10 and Pl. 38, Figs. 3 and 4. + + +LICMOPHORA LYNGBYEI (KUETZ.) GRUN. + +Frustule cuneate, slightly rounded at the angles. Valve oblanceolate; +pseudoraphe distinct; septa deep; striae, 12 in 10 [mu] below, and 16 in 10 +[mu] above. + +_Podosphenia lyngbyei_ Kuetz. + +Along the coast. + +Pl. 9, Figs. 3 and 4. + + +LICMOPHORA EHRENBERGII (KUETZ.) GRUN. + +Frustule cuneate, broad. Valve obovate-lanceolate; pseudoraphe wide; striae +coarse, 8 in 10 [mu], moniliform. + +_Podosphenia ehrenbergii_ Kuetz. + +Along the coast. + +Pl. 9, Fig. 5. + + +MERIDION AG. (1824) + +(merizo, I divide) + +Frustules in zone view cuneate, adnate in circular or spiral fasciae, at +length becoming free. Valve symmetrical with respect to the longitudinal +axis, more or less cuneate; costae and striae transverse. + +Chromatophores numerous, small, elongated, in irregular rows on the zone +(Pfitzer). + + +MERIDION CIRCULARE (GREV.) AG. + +Transverse costae coarse, variable in number and distance apart, sometimes +interrupted or indistinct; striae interstitial, 16 in 10 [mu]. + +In springs and small streams of pure water. + +_Echinella circularis_ Grev. + +{41}Meridion constrictum Ralfs, sometimes given as a variety of M. +circulare, differs only in the constriction below the apex. The two kinds +of frustules are usually found growing together and as the variation is +often extremely slight they are here included under the earlier name. + +Pl. 10, Figs. 1, 2 and 3. + +Fig. 1 represents the constricted form which is the more common. Fig. 3 is +a sporangial form. + +The sporangial frustules vary in shape and size, some being long and +slender, others clavate, but they are all more or less tumid in the middle, +with costae more indefinite than in perfect valves. All gradations occur, +one end becoming shorter until the valve has the shape of the variety known +as constrictum. It would seem, therefore, that the non-constricted form is +a passage from the sporangial to the smaller or adult form, or is of no +specific importance. All forms are found living together. The adult +frustules are the smaller ones; it is from them that the sporangia are +produced. + +Meridion intermedium H. L. Smith (Amer. Quart. Mic. Jour., Vol. 1, p. 12) +is characterized by less evident costae and is more delicate in general +appearance. Some forms are capitate and others are not. Prof. Smith +compares the M. intermedium with Peronia erinacea Breb. and Arnott which he +has named M. erinaceum, hitherto found only in Europe, and points out the +relation of the two forms to Licmophora. An examination of the H. L. S. +type slides of the two diatoms proves that Peronia has very delicate costae +and a distinct pseudoraphe not noticeable in Meridion. On the slide of +Peronia are frustules exactly similar to certain of the sporangial +variations of M. circulare. + +The fan-like arrangement of Licmophora, the marine form, and the circular +chains of Meridion, the fresh-water genus, are similar. Both are stipitate +at the beginning of their growth. + + + +(_c_) FRAGILARIEAE + +Divided into three sections: + +_Diatominae._--Valve circular, elliptical to linear, quadrate or cruciform, +with transverse costae; without raphe, a pseudoraphe sometimes wanting. + +_Fragilariinae._--Valve elongate, with small central and terminal +elevations, without costae but with transverse punctate striae; without +genuine central nodule. + +_Eunotiinae._--Valve lunate; a raphe sometimes partially formed with +terminal nodules near the edges. + + + +DIATOMINAE + +_Diatoma._--Frustules in filaments. Valve linear or elliptical, costate. + +_Plagiogramma._--Frustules in fasciae or free. Valve costate. + +_Opephora._--Valve costate, with an inner punctate stratum. + + +DIATOMA DE CANDOLLE (1805) em. HEIB. (1863) + +(diatemno, I cut in two) + +Frustules oblong or quadrate, adnate in filaments, attached by alternate +angles and finally separating. Valve linear or elliptical, with transverse +costae and rows of puncta and a pseudoraphe. + +Chromatophores large granules without definite arrangement. (See Pl. 40, +Fig. 11.) + + +{42}DIATOMA VULGARE BORY. + +Valve elliptical-lanceolate, with apices sometimes rostrate or capitate; +pseudoraphe narrow; costae, 5 in 10 [mu]. + +Common everywhere in pure fresh water and extremely variable. + +Pl. 10, Figs. 9 and 10. + +Var. elongatum (Ag.) = var. ehrenbergii (Kuetz.)--elliptical-lanceolate, +constricted near the apex. + +Var. grande (Wm. Sm.) Grun.--linear, elongated, constricted near the +apices. + +Pl. 10, Fig. 4. + +Both of these varieties, with numerous intermediate forms, are abundant +near Newtown Square. Varieties of Grunow, known as breve, ovate-lanceolate; +productum, ovate-lanceolate with produced apices; capitulatum, lanceolate +with capitate extremities, are mingled together in the same gathering. + + +DIATOMA ANCEPS (EHR.) KIRCHN. + +Valve linear with rostrate apices; costae robust; striae delicate, 20 in 10 +[mu]. Zone view quadrangular. + +Common in fresh water. + +Pl. 10, Figs. 5 and 6. Fig. 11, Pl. 40, shows frustules containing the +nuclei and chromatophores. + + +DIATOMA HIEMALE (LYNG.) HEIB. + +Valve ovate-lanceolate to lanceolate; apices obtuse, not produced. Costae +not numerous, robust; striae moniliform. Zone view quadrate, the costae as +septa deeply dividing the valve into convex elevations. + +Common in springs. + +Pl. 10, Figs. 7 and 8. + +In all species of Diatoma a punctum, or pore, is observed, usually at +alternate ends of the two valves, by means of which a communication exists +between adjoining frustules and causes them to adhere in zig-zag chains +when partially separated. + + +PLAGIOGRAMMA GREV. (1859) + +(plagios, on the side, and gramma, a letter) + +Frustules quadrangular, adnate in fasciae, or free. Valve linear, +elliptical, or elliptical-lanceolate, divided by two or more median and two +terminal costae or with a central and two terminal hyaline spaces. + + + Valve with two median and two terminal costae: + + Linear, pseudoraphe distinct pygmaeum + + Linear, with striae at the ends wallichianum + + Ovate-lanceolate obesum + + Valve without costae but with central and terminal + nodules: pseudoraphe absent tessellatum + + +{43}PLAGIOGRAMMA PYGMAEUM GREV. + +Valve linear-elliptical; pseudoraphe distinct; rows of granules transverse, +usually six in each compartment, moniliform, three on each side. + +Blue clay. Not common. + +Pl. 10, Fig. 13. + + +PLAGIOGRAMMA WALLICHIANUM GREV. + +Valve linear, rounded at the ends; pseudoraphe absent; transverse rows of +granules, six or seven in each compartment, and two or three rows of +smaller granules at each end. + +Blue clay. Not common. + +Pl. 10, Fig. 14. + + +PLAGIOGRAMMA OBESUM GREV. + +Valve rhombic-lanceolate, the costae scarcely visible; pseudoraphe rather +wide; rows of granules, about seven in each compartment, slightly +radiating. + +Blue clay. Not common. + +Pl. 10, Fig. 12. + + +PLAGIOGRAMMA TESSELLATUM GREV. + +Valve elliptical-lanceolate; central space transversely elliptical to the +major axis, half the diameter of the valve; terminal spaces more or less +circular or ovate. Granular markings large, quadrangular, in transverse +rows. Pseudoraphe not distinct. As the central space does not reach the +margin, it is a question whether this form is a Plagiogramma or a new +genus. + +Blue clay. Rare. + +Pl. 10, Fig. 11. + + +OPEPHORA PETIT (1888) + +(ope, an opening, and phoreo) + +Frustule rectangular. Valve cuneiform, linear or elliptical-lanceolate, +with broad, transverse striae and a well-defined pseudoraphe or median +area. + +The genus "portant des stries en forme de boutonnieres," as Petit remarks, +is quite near Fragilaria, under which the species here described were +originally included. (See Schmidt's Atlas, Pl. 298, where numerous forms of +F. pinnata are figured.) + + +OPEPHORA SCHWARTZII (GRUN.) PETIT + +Valve obovate-lanceolate or nearly linear with rounded apices; striae +transverse, broad, 3 or 4 in 10 [mu]; median area lanceolate. + +An inner stratum, with puncta in transverse rows, is apparent. + +Blue clay. Not uncommon. Variable in size. + +Pl. 10, Figs. 16 and 19. + + +OPEPHORA PACIFICA (GRUN.) PETIT + +Valve linear, oblong, with rounded apices. Median area linear, narrow; +striae punctate. + +Blue clay. + +Pl. 10, Fig. 18. + +Petit (Diat. Cap Horn) in his diagnosis states that the valves are +cuneiform, but they are not always so. + + +{44}OPEPHORA PINNATA VAR. LANCEOLATA N. VAR. + +Valve lanceolate; costae slightly radiate, punctate; median area broad, +lanceolate. + +Differs from O. pinnata in outline, radiation of the costae and median +area. + +Blue clay. Rare. + +Pl. 10, Fig. 17. + + + +FRAGILARIINAE + +_Fragilaria._--Frustules in fasciae. Valve with transverse striae. +Pseudoraphe indistinct. + +_Rhaphoneis._--Striae radiate; pseudoraphe distinct. + +_Dimerogramma._--Pseudoraphe broad. + +_Trachysphenia._--Valve cuneiform. + +_Synedra._--Valve elongate. + +_Asterionella._--Frustules in star-shaped clusters. + + +FRAGILARIA (LYNG.) RAB. + +(fragilis, because of the fasciae easily breaking up) + +Frustules rectangular, adnate in fasciae, soon breaking up. Valve +lanceolate, oblong or elliptical in general outline, with convex or sinuate +margins; without costae; pseudoraphe narrow or indistinct; striae +transverse. Chromatophores vary according to species. In some they consist +of four bands on the valves; in others they are granular (Mereschkowsky). + +Brun divides the genus into two sections, Fragilaria proper and Staurosira. +The former, with an indistinct pseudoraphe, includes the species virescens, +arctica, undata and linearis, while the latter, with distinct pseudoraphe, +includes capucina, harrisonii, construens and parasitica. + + +FRAGILARIA VIRESCENS RALFS + +Frustules in long fasciae. Valve elliptical-lanceolate, obtuse at the +apices; pseudoraphe indistinct; striae, 17 in 10 [mu], punctate. + +Very common in springs and pure streams. The fasciae are often a foot or +more in length. + +Pl. 10, Figs. 20 and 21. + + +FRAGILARIA ARCTICA GRUN. + +Valve oblong or elliptical, 10 [mu] in length; striae subtle, with coarse, +short striae at intervals on the margin and evident in zone view. + +Marine. Common at Cape May, N. J. + +Pl. 10, Figs. 22 and 23. + + +FRAGILARIA UNDATA WM. SM. + +Valve in general outline linear-elliptical, with extremities produced; +striae subtle; pseudoraphe distinct. + +Fresh water. + +Pl. 10, Figs. 24, 25, 27, 28 and 29. + + +{45}FRAGILARIA LINEARIS CSTR. + +Valve linear, with rounded apices; striae subtle; pseudoraphe indistinct. + +Marine. Cape May. + +Pl. 10, Fig. 37. Fig. 36 is an indeterminate form occasionally found in the +blue clay. + + +FRAGILARIA CAPUCINA VAR. MESOLEPTA RAB. + +Valve linear, constricted at the hyaline middle; apices slightly produced; +striae, 17 in 10 [mu]. Quite variable in size. + +Schuylkill River. Morrisville (Keeley). + +Pl. 10, Fig. 34. + + +FRAGILARIA HARRISONII (WM. SM.) GRUN. + +Frustules rectangular, solitary or in twos. Valve cruciform; pseudoraphe +narrow, lanceolate; striae robust, radiating in the middle, composed of +confluent puncta, larger at the circumference. + +Blue clay. + +Pl. 10, Fig. 31. + + +FRAGILARIA CONSTRUENS (EHR.) GRUN. + +Valve in general outline lanceolate, with produced apices; pseudoraphe +lanceolate, distinct or broad; striae subtle, 15 in 10 [mu]. L. of valve, +10-45 [mu]. + +_Staurosira construens_ Ehr. + +_Odontidium tabellaria_ Wm. Sm. + +Blue clay. + +Pl. 10, Fig. 30. + + +FRAGILARIA PARASITICA (WM. SM.) + +Frustules solitary or in twos. Valve lanceolate, sometimes constricted in +the middle; pseudoraphe wide, lanceolate; striae subtle. Parasitic on other +diatoms. + +_Odontidium parasiticum_ Wm. Sm. + +Not common. Media (Palmer). + +In the constricted form it is known as F. construens var. binodis (Ehr.) +Grun. + +Pl. 10, Fig. 35. + +An examination of the synonymy of the species of Fragilaria will convince +the student of the difficulty of determining the correct name even in +well-known forms. If all of the species of Fragilaria proper have granular +chromatophores, and all of Staurosira are placcochromatic, a satisfactory +division can be made, but so long as these facts are not known in all +species, and as authors have repeatedly confused the two divisions, the +nomenclature will be uncertain. F. harrisonii is probably in any case to be +separated from the others. De Toni includes it under its original name of +Odontidium, which genus he places near to Diatoma. The number of species in +our locality is too limited to render further discussion of any value. + + +{46}RHAPHONEIS EHR. (1844) + +(rhaphis, a needle) + +Frustule in zone view linear. Valve lanceolate or elliptical-lanceolate; +pseudoraphe distinct; striae radiating, moniliform. + + +RHAPHONEIS AMPHICEROS EHR. + +Valve lanceolate, broad, with apices produced; striae in curved lines, +moniliform, the large granules in longitudinal lines. + +Blue clay. + +Pl. 10, Fig. 38. + + +RHAPHONEIS AMPHICEROS VAR. RHOMBICA GRUN. + +Valve as in type form but shorter, with larger and more remote granules. + +Blue clay. + +Pl. 10, Figs. 39 and 40. + + +RHAPHONEIS BELGICA VAR. INTERMEDIA GRUN. + +Valve lanceolate, rostrate; granules in longitudinal and nearly transverse, +not radiating, lines. + +Absecon, N. J. + +Pl. 10, Fig. 41. + + +DIMEROGRAMMA RALFS (1861) + +(dis, two, meros, a part, gramma, a letter) + +Frustules quadrangular, inflated at the angles, in fasciae. Valve ovate or +lanceolate; striae moniliform, transverse or slightly radiate; median area +or pseudoraphe broad, lanceolate. + + +DIMEROGRAMMA MARINUM (GREG.) RALFS + +Valve lanceolate or linear and inflated in the middle; striae moniliform, +transverse or slightly radiate; median area linear or lanceolate, sometimes +not reaching the smooth extremities; striae, 8 in 10 [mu]. + +Pl. 12, Figs. 9 and 10. + +Fig. 9 differs in its lanceolate outline, in having four puncta on each +side in a row, and in the striae which are radiate. + + +DIMEROGRAMMA SURIRELLA (EHR.) GRUN. + +Valve elliptical-lanceolate, with rounded apices; striae moniliform, +radiate; pseudoraphe narrow, lanceolate. + +Blue clay. + +Pl. 12, Fig. 11. + + +{47}DIMEROGRAMMA MINUS (GREG.) RALFS + +Valve rhombic-lanceolate; striae punctate, radiate; pseudoraphe lanceolate; +apices smooth. + +Blue clay. Along the coast. + +Pl. 12, Figs. 12, 13, 14. + + +TRACHYSPHENIA PETIT (1877) + +(trachys, rough, and sphen, a wedge) + +Frustules rectangular. Valve cuneiform with coarse puncta in transverse and +longitudinal lines; pseudoraphe narrow, linear. One species only. + + +TRACHYSPHENIA AUSTRALIS PETIT + +Characters of the genus. Valve small; puncta, 6 in 10 [mu]. Allied to +Dimerogramma. + +Shark River, N. J. Rare. + +Pl. 12, Fig. 15. + + +SYNEDRA EHR. (1830) + +(synedrion, a sitting together) + +Frustules adnate in small stipitate clusters or free. Valve elongate, +linear or linear-lanceolate; pseudoraphe distinct; costae absent. + +The genus Synedra has few distinctive characters. As Brun remarks (Diat. +des Alpes et du Jura, p. 122), the dilatation of the extremities and the +pseudo-nodule are of little value in classification, as the intermediate +forms are so numerous. Fragilaria occurs in very long ribbons or fasciae, +Synedra in short fasciae or radiating clusters. Fragilaria is seldom longer +than three or four times the width, while Synedra is nearly always so. The +former has fine, often subtle, markings and narrow pseudoraphe, while the +latter has coarser punctate striae and a more distinct pseudoraphe. + +Chromatophores usually consist of two bands, one on each of the valves. +Karsten states that in the marine forms the chromatophores are oval or +polygonal discs, each of which usually encloses a pyrenoid. + + +SYNEDRA ULNA (NITZSCH) EHR. + +Frustules solitary or in twos. Valve 150-250 [mu] in length, linear or +linear-lanceolate, with rostrate apices; striae, 9 in 10 [mu]. + +Common in rivers and streams. + +Pl. 11, Figs. 4, 7 and 11 (?). + +Frequently interrupted in the middle. The distinction made by Wm. Smith as +to the presence or absence of the central blank space is probably not +necessary, as both forms are found which are otherwise identical. + +Fig. 5 represents the formation of a sporangial frustule which differs from +the usual form in its inflated ends prolonged into rostrate apices. Figs. 1 +and 6 are sporangial frustules. + + +{48}SYNEDRA BICEPS (KUETZ.) SCHMIDT + +Valve sublanceolate, inflated at the ends, apices rounded; central space +not always distinct; pseudoraphe narrow; striae radiate at the ends. + +This is not Kuetzing's species, if the descriptions and figures are +accepted, nor is it H. L. Smith's Type No. 545, which is S. ulna var. +danica, nor is it S. biceps Wm. Smith, but it is exactly Schmidt's form +(Atlas, Pl. 303, Figs. 10-15). + +Schuylkill River. + +Pl. 11, Fig. 3. + + +SYNEDRA DANICA KUETZ. + +Valve lanceolate, suddenly constricted at the rounded apices; central space +frequently absent. + +Very common in streams. + +Pl. 11, Fig. 2. + +The figure represents an unusually large form. It differs from S. ulna only +in its apices. + + +SYNEDRA CAPITATA EHR. + +Valve long, linear, dilated into triangular acute apices; pseudoraphe +distinct; striae radiate at the ends. + +Blue clay. + +Pl. 11, Fig. 8. + + +SYNEDRA ACUS KUETZ. + +Valve very narrow, lanceolate, acicular, with obtuse apices. + +Common in the Schuylkill River. + +Pl. 11, Figs. 9 and 18. + + +SYNEDRA GOULARDI BREB. + +Valve constricted in the middle; apices sub-acute, sometimes slightly +rostrate or capitate; central space evident. + +Neshaminy Creek (Palmer). Blue clay. Crum Creek. + +Pl. 11, Figs. 12 and 13. + + +SYNEDRA PULCHELLA (RALFS) KUETZ. + +Valve lanceolate, tapering to the sub-acute, rostrate or slightly capitate +apices; dilated at the central hyaline space; pseudoraphe distinct. Very +variable in size. + +Crum Creek. Schuylkill River. Rather common. + +Pl. 11, Figs. 14, 15, 16. + + +SYNEDRA PULCHELLA VAR. ABNORMIS MACCHIATI? + +Valve as in type form, except that one end is curved like a beak, as in S. +hamata Wm. Sm., which it resembles. + +Not uncommon in the Schuylkill River. + +Pl. 11, Fig. 17. + + +SYNEDRA OXYRHYNCHUS VAR. UNDULATA GRUN. + +Valve linear-lanceolate with produced rostrate apices, asymmetrical, +sigmoid; pseudoraphe narrow; pseudo-nodule large. + +Common in fresh water. + +Pl. 12, Fig. 1. + + +{49}SYNEDRA PULCHELLA VAR. FLEXELLA N. VAR. + +Frustule slightly attenuated at the ends, truncate, somewhat tumid in the +middle and flexed. Valve lanceolate, with obtuse or subcapitate apices and +with two almost imperceptible constrictions at the middle producing a tumid +appearance; pseudoraphe distinct; pseudo-nodule absent. L. 56 [mu]; striae, +14-16 in 10 [mu]. + +Some valves are bent and incised on one side. The outline of the valve is +that of pulchella. + +Common at Newtown Square. + +Pl. 12, Fig. 2. + + +SYNEDRA RADIANS KUETZ. + +Frustules linear, in small fasciae. Valve 34 [mu] in length, linear, with +apices rostrate, obtuse, sometimes slightly capitate; pseudoraphe distinct; +striae about 20 in 10 [mu]. + +Fresh water. + +Pl. 10, Figs. 32 and 33. + +There is difficulty in recognizing S. radians K. as described and figured +by different authors. On Plate 12, Fig. 8, I have drawn a specimen from H. +L. Smith's Type Slide No. 574, labelled S. radians Kuetz., not Wm. Smith, +which, however, corresponds closely to Smith's figure (Brit. Diat. 1, Pl. +11, Fig. 89). De Toni gives S. radians Kuetz. as equivalent to S. tenera +Wm. Sm. Van Heurck's figure of S. radians, and also the figure of ulna +var., said to be synonymous with H. L. Smith's S. radians, which does not +correspond to the specimens on Smith's slide in my possession, are +confusing. In Van Heurck's Synopsis the striae are said to be 16 or 17, +while De Toni describes them as subtle and from 17 to 24 in 10 [mu]. The +length is quite variable. + +Several species of Synedra resemble S. radians in the mode of growth, as +they are adnate at first, in short bands, the frustules being sessile on +other plants or objects, attached at the terminal nodules which, although +scarcely visible in most forms, are probably present in all. The frustules +are not closely connected at the free end, and soon become entirely +detached. + +In Diatoma and Fragilaria, we find a punctum or pore at one end of a valve, +but not in line with the pseudoraphe; in Synedra, a minute pore is usually +found in the position of the terminal nodule and, in some species, +indications of a central nodule are observed; the median line is wider but +there is no raphe. In the fresh-water Synedrae, many of which are among the +longest of diatoms, living in running streams, the terminal nodules are +much more indistinct, while the marine forms have distinct terminal +nodules, are not, as a rule, found in bands, and assume a more naviculoid +outline. + + +SYNEDRA VAUCHERIAE VAR. PARVULA (KUETZ.) RAB. + +Valve lanceolate, with produced or rostrate apices; pseudo-nodule wide, +excentric. L. 17 [mu]. + +Crum Creek. + +Pl. 12, Fig. 5. + +Fig. 6 represents a variety with coarser striae from the Schuylkill River. +Both are easily mistaken for Fragilaria intermedia. + + +{50}SYNEDRA FULGENS (GREV.) WM. SM. + +Frustules geminate or flabellate on a stipe. Valve slightly inflated in the +middle and at the apices; pseudoraphe narrow; striae finely punctate, +radiate at the ends. + +Marine. Atlantic City. + +Pl. 11, Fig. 10. + + +SYNEDRA AFFINIS KUETZ. + +Valve lanceolate; striae marginal, leaving a broad lanceolate pseudoraphe. + +Common along the coast. + +Pl. 12, Fig. 3. + + +SYNEDRA AFFINIS VAR. PARVA (KUETZ.) V. H. + +Valve lanceolate, slender; striae marginal, shorter than in the type. + +_Synedra gracilis_ Kuetz. + +Common along the coast. + +Pl. 12, Fig. 7. + + +SYNEDRA AFFINIS VAR. TABULATA (AG.) V. H. + +Valve linear-lanceolate; striae, 11 in 10 [mu], very short. + +Not common. New Rochelle. + +Pl. 12, Fig. 4. + + +ASTERIONELLA HASSALL (1855) + +(dim. of aster, a star) + +Frustules linear, slightly inflated at the ends, arranged in star-shaped +clusters which soon break up. Valve linear, unequally inflated at the ends. + + +ASTERIONELLA FORMOSA HASS. + +Valve clavate at the ends; striae transverse, 17 in 10 [mu], pseudoraphe +very narrow or indistinct; an ovoid, hyaline area at each end. + +Newark, N. J. Broomall's Lake, Media (Palmer). + +Pl. 12, Figs. 19, 20, 21. + + +ASTERIONELLA INFLATA HEIB. + +Valve linear, capitate at each end and tumid in the middle; striae +distinctly punctate; pseudoraphe indistinct, or not apparent. L. 30 [mu]. + +Fresh water. May's Landing, N. J. + +Pl. 12, Fig. 22. + + + +EUNOTIINAE + +_Eunotia._--Frustules either free, in fasciae or epiphytic. Valves arcuate. + +_Actinella._--Frustules, solitary or in small clusters, cuneate. Valve +inflated at one end. + + +{51}EUNOTIA EHR. (1837) em. GRUN. (1862) + +(eu, well, and noton, a back, referring to the strong, ridged dorsum) + +Frustules free, in fasciae or epiphytic. Valve arcuate, without costae, +transversely striated; pseudoraphe absent; pseudo-nodules at each end. + +Chromatophores laminate along the concave zone and the valves. + +Very many species of Eunotia have been created to differentiate size and +number of crenae or undulations. An examination of certain fossil deposits +of New England, as well as a gathering from the blue clay of Philadelphia, +will show forms which vary infinitely. E. major and E. gracilis are +scarcely distinguishable because of the intermediate variations. The striae +in all forms are punctate, but the puncta are frequently confluent. + + +ANALYSIS OF SPECIES + +Eunotia is divided into two sections, Himantidium and Eunotia proper. In +Himantidium, the frustules are in fasciae, either short or long. Among +those with short fasciae are major, gracilis, and nymanniana; those with +long fasciae are pectinalis, solierolii and veneris. Eunotia proper +includes frustules, free or epiphytic, in which the valves are not dentate +on the dorsal margin, such as lunaris, hemicyclus, biceps and praerupta; +and those in which the valves are dentate or crenate on the dorsum, such as +monodon, triodon, diadema and others. + +The resemblance between Eunotia and Epithemia is noticeable. In both, the +epiphytic character of the valve is seen in the shape of the frustule which +is arched, and, in the free forms, is adherent at the ends only. In +Epithemia, the median is more evident than the terminal nodules. In +Eunotia, there is no median nodule, but the end nodules, in some species, +are quite evident, and a tendency is shown to produce a very short raphe. +The arrangement of puncta in valve view is similar in both genera. + + +SECTION 1. HIMANTIDIUM + +EUNOTIA MAJOR (WM. SM.) RAB. + +Valve arcuate, linear, subcapitate, recurved. Striae punctate, 12 in 10 +[mu] L. 90-190 [mu]. + +Common in fresh water. + +Pl. 13, Figs. 1 and 2. + + +EUNOTIA GRACILIS (EHR.) RAB. + +Valve with sides parallel; apices slightly capitate and revolute; striae, +10 in 10 [mu]. The striae on the connective membrane more delicate than in +E. major. Intermediate forms occur. + +Common in fresh water. + +Pl. 13, Fig. 3. Fig. 4 is indeterminate. + + +EUNOTIA NYMANNIANA GRUN. + +Valve small, curved, with parallel dorsal and ventral margins; apices +truncate and recurved into dorsal elevations; striae delicate. + +Blue clay. Not common. + +Pl. 13, Fig. 32. + + +{52}EUNOTIA PECTINALIS (KUETZ.) + +Valve linear, arcuate, apices slightly rostrate; striae distinctly punctate +with puncta in longitudinal rows nearer together at the ends. + +_Himantidium pectinale_ Kuetz. + +Common in fresh water. + +Pl. 13, Figs. 6 and 7. + +The fasciae are associated in large masses, sometimes an inch or more in +diameter, and late in August are found a foot or more in length, of a +beautiful chocolate color. Exceedingly abundant in the cedar-swamp streams +of the Pine Barren regions of New Jersey. In winter, the dead frustules +form a parchment-like coating upon the twigs, dead leaves, and other debris +on the borders of streams. + +This species can scarcely be referred to Dillwyn's Conferva pectinalis, as, +in his description, quoting Mueller, he says that "the filaments are of a +dirty green color; seldom exceeding half an inch in length." Dillwyn's form +is probably Fragilaria virescens, which equals Fragilaria pectinalis Ehr., +while Kuetzing's species is Fragilaria pectinalis Ralfs. It is not +impossible to confuse Fragilaria virescens and Eunotia pectinalis when the +zone only is seen under a low power and their mode of growth is similar. + + +EUNOTIA PECTINALIS VAR. UNDULATA RALFS + +Valve as in type form, but with undulate margins. + +Common in the cedar swamps of New Jersey. + +Pl. 13, Figs. 8 and 10. + + +EUNOTIA PECTINALIS VAR. SOLIEROLII (KUETZ.) + +Valve as in type, but with internal divisions as though in the process of +reduplication. + +Not common. Moorestown, N. J. (Palmer). + +Pl. 13, Fig. 9. + + +EUNOTIA PECTINALIS VAR. VENTRICOSA GRUN. + +As in type, but with the valves tumid in the middle. + +May's Landing, N. J. + +Pl. 13, Fig. 12. + +Fig. 11 is a form found in the blue clay. It differs in the coarser puncta +from the var. ventricosa. In outline it resembles Eunotia arcus Wm. Sm., +which is Ceratoneis arcus (Ehr.) Kuetz., but the central nodule is not +present as in the latter form, which connects Eunotia and Cymbella. It may +be a form of E. luna Ehr. (A. S., Atlas, Pl. 286, Figs. 33 and 34.) + + +EUNOTIA VENERIS KUETZ. + +Valve with convex dorsal and straight ventral margins, more or less +constricted near the sub-acute apices. Striae subtle, punctate. + +_Eunotia incisa_ Greg. + +May's Landing, N. J. Blue clay, Pavonia, N. J. + +Pl. 13, Figs. 30 and 31. + + +{53}EUNOTIA (PROPER) + +EUNOTIA LUNARIS (EHR.) GRUN. + +Frustules sessile, solitary or in clusters. Valve arcuate, narrow, +attenuated toward the apices, which are sometimes slightly rostrate or +rostrate-capitate; transverse striae, 14 in 10 [mu], punctate. + +Very common in ditches, especially in the spring. Variable in length. + +Pl. 12, Figs. 24 and 25. + + +EUNOTIA HEMICYCLUS (EHR.) RALFS + +Valve semicircular, with obtuse apices; striae transverse, punctate; +terminal nodules minute and indistinct. + +Hammonton Pond, N. J. Rare. + +Pl. 12, Fig. 23. + +The genus Pseudo-Eunotia was created by Grunow for forms like Eunotia, but +without terminal nodules. As, however, in E. lunaris and E. hemicyclus +nodules are evident, although not so large as in many species, I include +these two forms as heretofore under Eunotia. + + +EUNOTIA BICEPS EHR. + +Valve linear, slightly arcuate, narrow, with rounded apices somewhat +revolute; striae, 16 in 10 [mu]. + +May's Landing, N. J. + +Pl. 13, Fig. 27. + + +EUNOTIA PRAERUPTA EHR. + +Valve convex on dorsal side, apices dilated and truncate; striae distant at +centre. + +Common in the blue clay. + +Pl. 13, Fig. 5. + + +EUNOTIA PRAERUPTA VAR. BIDENS GRUN. + +Valve with two undulations; otherwise as in type. + +_Eunotia bigibba_ Greg. + +With the type. + +Pl. 13, Fig. 19. + + +EUNOTIA ROBUSTA RALFS + +Valve arcuate, with several or numerous dorsal ridges or crenae which +decrease in relative size in proportion to their number. Striae radiate, +variable in distance apart, and in size of puncta. + +Ralfs included under this one name the following species named by +Ehrenberg: E. diodon (2 crenae); E. triodon (3); E. tetraodon (4); E. +pentodon (5); E. diadema (6); E. heptodon (7); E. octodon (8); E. enneadon +(9); E. decadon (10); E. hendecadon (11); E. duodecadon (12); E. serra +(13); E. prioritis (14); all more than 20, E. polyodon. E. scalaris, with +from 15 to 17 crenae, and E. icosodon with 20, may be added. + +It is probable that all of these forms occur at May's Landing, N. J. The +forms with more than eight crenae are comparatively rare. In the blue clay +those with from four to six are most common. + +Pl. 13, Figs. 13, 14, 15, 16, 17, 21, 24, 25. + + +{54}EUNOTIA BACTRIANA EHR. + +Valve linear, apices revolute, acute, dentate on the dorsal margin, with +one acute crena near each end. + +Tom's River, N. J. Rare. + +Pl. 13, Fig. 18. + + +EUNOTIA BIDENTULA WM. SM. + +Valve with straight ventral margin, and with two undulations on the dorsum; +apices large, rounded. + +May's Landing, N. J. Rare. + +Pl. 13, Fig. 20 (not Schumann's form, which has angular crenae). + + +EUNOTIA FORMICA EHR. VAR.? + +Valve turgid in the middle and at the apices which are unilaterally +truncate. + +Pensauken, N. J. (artesian well). + +Pl. 13, Fig. 26 (not a typical form). + +The following are forms which appear to be indeterminate, or, in any case, +are scarcely worthy of distinction by specific names, as might be said of +others of the innumerable variations of this genus: + +Fig. 23, Pl. 13, probably a form of praerupta. Newtown Square. + +Fig. 28, Pl. 13, from the blue clay. + +Fig. 29, Pl. 13, an asymmetrical form, apparently abnormal, but not rare at +May's Landing, N. J. + +Fig. 17, Pl. 38. Valve convex on the dorsal side, incised on the ventral; +striae about 15 in 10 [mu], closer at the ends; L. 30 [mu]. Schuylkill +River. + +Fig. 18, Pl. 38. Valve arcuate, asymmetrical, broader at one end; terminal +nodules large; striae, 10 in 10 [mu]; L. 47 [mu]. Gloucester, N. J., +artesian well. + +Numerous variations of the above species are illustrated in Schmidt (Atlas, +Pls. 285-291). + + +ACTINELLA LEWIS (1865) + +(dim. of actin, a ray) + +Frustules solitary, or in small clusters, sub-cuneate or nearly linear. +Valve arcuate, rounded at one end and suddenly widened at the other into a +cup-shaped or lychnoid inflation. + + +ACTINELLA PUNCTATA LEWIS + +Valve with fine, transverse striae; on the margin, puncta at intervals; +terminal nodules distinct. + +May's Landing, N. J. + +Pl. 12, Figs. 16, 17, 18. + +Fig. 17, from Tom's River, N. J., is an approach toward A. brasiliensis +Grun. + +Fig. 18 represents the frustules geminate, a frequent occurrence. + + + +{55}NAVICULOIDEAE + +In discussing the Naviculoid group, the general divisions of Cleve are here +followed, and all diatoms having a true raphe are included. I have added +the genus Epithemia and also Rhopalodia, partly because they contain a +raphe of a certain kind and partly because they resemble the markings of +certain of the genus Hantzschia in the following group, although in other +respects there is probably no similarity. + +The difficulty of combining the numerous genera into groups which are +naturally affiliated is avoided in the following arrangement based on +superficial similarities, and is intended merely as an artificial key. To +unite all forms having a raphe and which are symmetrical with valves +similar and not sigmoid, under the one genus Navicula, as has been the +custom previous to the publication of Cleve's monograph, would result in +associating species differing in so many respects in relation to structure +of the valve and cell contents that it seems advisable to retain the new +genera, especially as the original genus is likely to be still further +reduced when more is known of the structure and life history of the group. + + +KEY TO THE GENERA + + + Valves dissimilar. Achnantheae + + symmetrical Cocconeis + + asymmetrical + + to the longitudinal axis Anorthoneis + + to the transverse axis Rhoicosphenia + + in zone view Achnanthes + + Valves similar and asymmetrical + + asymmetrical to the longitudinal axis + + valves parallel Cymbella + + valves not parallel Amphora + + valves keeled, twisted (sometimes symmetrical) Amphiprora + + valves keeled Tropidoneis + + valves reniform and keeled Auricula + + median line sigmoid at the ends Scoliotropis + + asymmetrical to the transverse axis + + striae punctate and costate Gomphoneis + + striae punctate Gomphonema + + Valves similar, symmetrical and sigmoid + + striae oblique Pleurosigma + + striae at right angles Gyrosigma + + Valves similar, symmetrical, not sigmoid + + striae punctate, nodules elongated Frustulia + + striae subtly punctate, central nodule forked Amphipleura + + striae punctate and reticulate, in two strata Dictyoneis + + striae punctate and alveolate, in three strata Trachyneis + + striae punctate, in two strata Brebissonia + + striae interrupted by blank lines Anomoeoneis + + striae crossed by longitudinal lines Caloneis + + striae oblique, median fissures in opposite directions Neidium + + striae punctate and costate, median line with horns Diploneis + + striae punctate; valves separated by septate plates Mastogloia + + striae punctate, central area dilated into a stauros Stauroneis + + striae punctate, area without stauros or horns Navicula + + striae costate, not punctate Pinnularia + + + +{56}ACHNANTHEAE + +Frustules stipitate, free or parasitic. Valves cuneate, elliptical or +suborbicular, dissimilar, bent along the transverse or the longitudinal +axes, the lower valve with a true raphe and central and terminal nodules, +the upper valve with a pseudoraphe or median line. + +_Rhoicosphenia._--Stipitate; valves with transverse puncta, bent along the +transverse axis, cuneate, with diaphragms at the ends. + +_Anorthoneis._--Free; puncta radiate; valves bent slightly along the +transverse axis, suborbicular. + +_Cocconeis._--Parasitic; valves elliptical, usually bent along the +longitudinal axis; striae punctate, transverse and longitudinal. + +_Achnanthes._--Stipitate; valves lanceolate or elliptical, bent along the +transverse axis; striae transverse, punctate; costae sometimes present. + + +RHOICOSPHENIA GRUN. (1860) + +(rhoicos, curved, and sphen, a wedge) + +Frustule in zone view curved; valves cuneate, dissimilar, the upper with a +pseudoraphe, the lower with a raphe. + +Chromatophore a single plate along both valves, and one of the inner walls +of the zone. Conjugation as in Gomphonema, with which it is generally +associated in classification. + + +RHOICOSPHENIA CURVATA (KUETZ.) GRUN. + +Valve clavate, with rounded apex and base; lower valve with raphe, a narrow +axial area and slightly radiate, punctate striae; the upper valve with a +narrow pseudoraphe and parallel striae; a short diaphragm at the ends of +each valve. Length usually from 15 to 25 [mu], but frequently of twice the +size. + +Common in Crum Creek. + +Pl. 19, Figs. 25, 26, 27. + + +ANORTHONEIS GRUN. (1868) + +(anorthos, not straight) + +Valves dissimilar, the upper valve with an excentric axial area, the lower +with an excentric raphe. + + +ANORTHONEIS EXCENTRICA (DONK.) GRUN. + +Valves orbicular, with radiating, punctate striae, closer at the +circumference, producing the appearance of a border. Axial area not +reaching the ends. Frustules occur free on the sands of the sea-shore. L. +25 to 50 [mu]. + +Belmar, N. J. + +Pl. 16, Figs. 30 and 31. + + +{57}COCCONEIS EHR. (1835) em. GRUN. (1868) + +(coccos, a berry) + +Valves elliptical, dissimilar, the upper valve with a pseudoraphe and the +lower with a genuine raphe and nodules, usually with a rim or annulus. +Frustules epiphytic. + +Cocconeis is generally considered as a degenerated form of Mastogloia, as +indicated by the "obsoletely loculiferous rim." The frustules are usually +bent along the longitudinal axis, probably because of the attachment to the +curved stems of water-plants. + +The cell contents of only a few species are known. In C. pediculus, a +single chromatophore occurs on the inside of the upper valve. In +conjugation, two cells open and secrete a gelatinous mass from which an +auxospore is formed. + +Cleve separates the forms having a loculiferous rim (Cocconeis) from those +without a rim (Eucocconeis). As the rim is easily detachable, the +distinction is often made with difficulty. + + +COCCONEIS SCUTELLUM EHR. + +Valves elliptical, the upper with a linear or lanceolate pseudoraphe and +coarse puncta in transverse and radiating lines; the lower valve with much +finer puncta in radiating lines, a lanceolate axial area and, sometimes, a +loculiferous rim. + +Along the coast. Common, but extremely variable. + +Pl. 16, Fig. 21 (upper valve). Fig. 18, var. ? + + +COCCONEIS SCUTELLUM VAR. ORNATA GRUN. + +Upper valve with linear axial area, and transverse and radiating punctate +lines which end at the border in a double row of finer puncta; lower valve +with much finer puncta, a lanceolate axial area and a loculiferous rim. + +Atlantic City. Common. + +Pl. 16, Figs. 27 and 28. + +The forms along the coast vary infinitely both in size and appearance. The +var. ornata is very abundant along the entire coast. In any gathering, +valves are found with or without the rim which is frequently seen detached. +The upper valve is sometimes without the double row of puncta. Fig. 21 +represents an upper valve more coarsely punctate than usually occurs. Very +many intermediate forms might be noticed. + + +COCCONEIS PEDICULUS EHR. + +Valves rhombic-elliptical, very convex, somewhat asymmetrical; the upper +valve with a linear pseudoraphe, sometimes widened near the ends, and +slightly radiating, finely punctate striae; lower valve with narrow, axial +area and finely punctate, radiating striae. + +Not uncommon in fresh water. Abundant in a ditch at Paoli, Pa. + +Pl. 16, Figs. 23 and 24. + + +COCCONEIS PLACENTULA EHR. + +Valve elliptical; upper valve with a linear or lanceolate axial area, and +punctate striae in transverse and radiating rows, the puncta at equal +distances; the lower valve with a lanceolate axial area, radiating rows of +puncta, and a wide border of finely punctate, radiating striae, separated +from the central part of the valve by a narrow hyaline zone. + +Common in salt, brackish and fresh water. + +Pl. 16, Figs. 19 and 20. + + +{58}COCCONEIS PLACENTULA VAR. LINEATA (EHR.) V. H. + +As in the type, except that the upper valve has the puncta arranged in +zig-zag, giving the appearance of sinuous, longitudinal lines. + +Common along the coast. + +Pl. 16, Fig. 29. + +C. pediculus and C. placentula are the only species I have found in fresh +water. Cleve states that the former occurs also in brackish water. + +The following are among the species placed by Cleve in a new genus, +Eucocconeis, distinguished by the absence of a loculiferous rim. + + +COCCONEIS DIRUPTA GREG. + +Valves elliptical, the lower with fine puncta in slightly radiating lines, +a narrow axial area and a central area dilated into a lanceolate, +stauriform space; the terminal fissures turned in opposite directions; the +upper valve similar to the lower valve except in the absence of raphe and +nodules. + +Along the coast. New Rochelle. + +Pl. 16, Fig. 22 (lower valve). + + +COCCONEIS PELLUCIDA GRUN. + +Valves elliptical, the upper with broad axial area on each side of which +are fine, longitudinal rows of short striae; the lower valve with more +numerous longitudinal rows, a marginal line and indistinct raphe; the +terminal fissures small and turned in opposite directions. + +New Rochelle. + +Pl. 16, Figs. 25 and 26. + +In the var. minor Grun. the median line of the lower valve is sometimes +slightly sigmoid. + + +ACHNANTHES BORY (1822) + +(achne, froth or down, and anthos, a flower) + +Frustules stipitate, solitary or in short fasciae, flexed. Valves +elliptical or lanceolate, naviculoid, dissimilar, the lower with a raphe +and median and terminal nodules, and the upper with a pseudoraphe or median +space. + +The genus has no apparent affinity with any other. + + +ACHNANTHES LONGIPES AG. + +Valves linear-elliptical, obtuse at the apex, sometimes slightly +constricted in the middle. Connective zone with transverse, subtly punctate +striae, interrupted by longitudinal lines. Central nodule of lower valve +dilated into a stauros reaching the margin. Valves costate, the costae +alternating with double rows of fine puncta. + +Along the coast, in estuaries. + +Pl. 16, Figs. 1 and 2. + +A. longipes is the only species in our locality considered by Cleve as +belonging to the genus; the other forms, distinguished by the absence of +costae, are included in the genus Achnanthidium of Kuetzing. + +In A. longipes, the chromatophores consist of scattered, rounded granules, +while in Achnanthidium the chromatophore is a single plate along the upper +valve, or a double one {59}along the connective zone. It is necessary, +therefore, to distinguish between A. longipes and the following group, but, +because of the long continued union of all of the stipitate forms having +the general appearance of a true Achnanthes, I shall continue to describe +the local species under the generally accepted name. + + +ACHNANTHES BREVIPES AG. + +Valves without costae; striae moniliform; upper valve with excentric +pseudoraphe or median line; otherwise as in A. longipes. + +Along the coast, in estuaries. + +Pl. 16, Fig. 3. + + +ACHNANTHES SUBSESSILIS KUETZ. + +Valves linear-elliptical, rounded at the ends; upper valve with excentric +pseudoraphe; striae moniliform, puncta smaller than in A. brevipes. + +Along the coast, in estuaries. + +Pl. 16, Figs. 4, 5, 6. + +The three species described above are named from the length of the stipe, +but this varies considerably and is not of special significance. + + +ACHNANTHES INFLATA (KUETZ.) GRUN. + +Valves more or less inflated in the middle, usually with the stauros of the +lower valve asymmetrical and wider than in A. subsessilis, with which it +agrees in size and markings. + +Gloucester, N. J. (artesian well). + +Pl. 16, Figs. 7 and 8. + + +ACHNANTHES COARCTATA (BREB.) GRUN. + +Valves lanceolate, oblong, broad at the ends and constricted in the middle. +Stauros wide; pseudoraphe of the upper valve excentric; striae slightly +radiate on the lower valve; puncta small. + +Blue clay. + +Pl. 16, Fig. 9. + + +ACHNANTHES LANCEOLATA (BREB.) GRUN. + +Valves more or less elliptical; striae radiating, 12 in 10 [mu], punctate; +on the lower valve a horse-shoe shaped hyaline space on one side of the +centre; on the upper valve an irregular stauros, not reaching the margin. +L. 8-20 [mu]. + +In springs. Abundant at Newtown Square. + +Pl. 16, Figs. 10, 11, 12. + + +ACHNANTHES EXIGUA GRUN. + +Valves oblong-lanceolate, with rostrate ends, sometimes slightly +constricted in the middle. Stauros rather wide; striae punctate, radiating, +22 in 10 [mu]. L. 10-12 [mu]. + +_Stauroneis exilis_ Kuetz. (not Achnanthes exilis Kuetz.) + +Frequently found in aquaria where I have kept it growing continuously for +years. + +Pl. 16, Figs. 14 and 15. + + +ACHNANTHES LINEARIS FORMA CURTA H. L. SMITH + +Frustules solitary or geminate. Valves linear-elliptical, or +elliptical-lanceolate. Lower valve without distinct axial area; upper valve +with axial area widened in the middle; striae slightly radiate (?). L. 7 +[mu]. One of the smallest of diatoms. + +{60}This form I found in a pure gathering covering the sides of a +greenhouse tank at Elm, N. J. It was sent to Prof. H. L. Smith, who +determined it as forma curta of A. linearis. + +Pl. 16, Figs. 16 and 17. + + +ACHNANTHES DANICA (FLOEGEL) GRUN. + +Valves rhombic-lanceolate, with subacute ends. Striae, 25 in 10 [mu], +radiate. Lower valve with stauros widened toward the margin, and cleft into +three divisions. + +Pavonia, N. J. (artesian well). + +Pl. 16, Fig. 13. + +I have seen the lower valve only. Cleve states that the upper valve is +costate with "alternating fine lineolae twice as close as the costae." + + +CYMBELLA AG. (1830) + +(cymbe, a boat) + +Frustules free, stipitate or enclosed in tubes. Valve boat-shaped; median +line asymmetrical, straight or curved. + +Chromatophore single, covering the entire interior of the frustule, except +the ventral part of the zone and the median lines. Its longitudinal axis is +on the dorsal part of the zone. A pyrenoid lies in a fold of the +chromatophore on the dorsal part. + +The genus includes the former genera of Cocconema, characterized by +stipitate forms, and Encyonema in which the frustules are frequently +enclosed in gelatinous tubes. + + +SECTION 1.--CYMBELLA PROPER. FRUSTULES FREE OR SOMETIMES STIPITATE + +CYMBELLA HETEROPLEURA (EHR.) KUETZ. + +Valve nearly symmetrical, lanceolate, with rostrate, produced apices; +median line nearly straight; axial area linear, widened in the middle; +striae radiate, punctate. + +Blue clay. + +Pl. 18, Fig. 10. + + +CYMBELLA CUSPIDATA KUETZ. + +Valve broad, elliptical, with rostrate, somewhat acute, apices and nearly +straight, ventral margin; median line straight, axial area linear, widened +in the middle; striae radiate, punctate. + +Blue clay. + +Pl. 18, Fig. 17. + + +CYMBELLA NAVICULIFORMIS AUERSWALD + +Valve linear-elliptical, with abruptly produced apices; ventral margin +straight; median line almost straight; axial area narrow, central area +large, rounded; striae distant in the middle, closer at the ends. + +Fresh water. + +Pl. 18, Fig. 6. + + +CYMBELLA EHRENBERGII KUETZ. + +Valve lanceolate, with ventral margin nearly straight and apices +sub-rostrate; median line straight, excentric; axial area narrow; central +area widened in the middle; striae coarsely punctate. + +Fresh water. + +Pl. 18, Fig. 9. + + +{61}CYMBELLA AFFINIS KUETZ. + +Valve about three times as long as broad, strongly convex on the dorsal +side and straight on the ventral; apices sub-rostrate; striae punctate; +axial area narrow, not widened in the middle; median line curved; a small +or indistinct punctum on the ventral side of the median line (not shown in +the figure). + +Common in ponds. Abundant in East Park Reservoir. + +Pl. 18, Fig. 18. + + +CYMBELLA EXCISA (KUETZ.) DE TONI + +Valve as in affinis, but with tumid and excised ventral margin; a punctum +is found on the ventral side (not shown in the figure). + +According to Cleve this is a variety of C. affinis. + +Common in ponds. + +Pl. 18, Figs. 15, 19? + + +CYMBELLA PARVA (WM. SM.) CL. + +Valve semi-lanceolate, with produced apices; ventral margin slightly tumid; +axial area narrow; striae coarsely but obscurely punctate. + +C. affinis and C. parva are quite variable, the latter differing by its +lanceolate form and the absence of a punctum, which, however, is sometimes +difficult to recognize. In a gathering of C. parva, it is quite possible to +find numerous abnormal forms which appear to be sporangial, so that +specific distinctions are difficult if based on occasional specimens. + +Common in ponds. + +Pl. 38, Fig. 14. + + +CYMBELLA AMPHICEPHALA NAEGELI + +Valve unequally elliptical, with broad, rostrate apices; axial area narrow; +median line straight; central area small, rounded; striae, 12 in 10 [mu] on +the dorsal, closer on the ventral, side and at the ends. + +Kirkwood Pond, N. J. + +Pl. 18, Fig. 16. + + +CYMBELLA SINUATA GREG. + +Valve linear-elliptical, gibbous on the ventral side; axial area +indistinct; central area widened on the ventral side nearly to the margin. + +Crum Creek. + +Pl. 18, Fig. 13. + + +SECTION 2.--COCCONEMA. FRUSTULES STIPITATE + +CYMBELLA ASPERA (EHR.) CL. + +Valve large, cymbiform, arcuate on the dorsal, slightly gibbous on the +ventral side; axial area linear, broad, slightly widened in the middle; no +row of puncta on the ventral side. The puncta form curved longitudinal +lines and the innermost row on the ventral side appears sometimes distant +from the others, but not as in C. cistula. + +_Cocconema asperum_ Ehr. + +_Cymbella gastroides_ Kuetz. + +{62}Not Cymbella gastroides H. L. Smith, Type No. 118, which is C. mexicana +A. S., having a punctum in the middle of the central nodule; in outline it +is like C. gastroides var. minor Kuetz. + +Blue clay. + +Pl. 18, Fig. 1 (an unusual form, but it resembles Grunow's. (Diat. Franz +Jos. Land, Pl. 1, Fig. 7.) + + +CYMBELLA CYMBIFORMIS (KUETZ.) BREB. + +Valve cymbiform, slightly gibbous on the ventral margin; apices broad, +somewhat truncate; a punctum occurs on the ventral side of the median line; +striae, 8 in 10 [mu], closely punctate. + +Kirkwood Pond, N. J. + +Pl. 18, Fig. 2. + + +CYMBELLA CISTULA (HEMPR.) KIRCHN. + +Valve cymbiform, with gibbous ventral margin and truncate apices; a +distinct row of several puncta occurs below the median line in typical +forms. + +Blue clay. + +Pl. 18, Fig. 3. + + +CYMBELLA LANCEOLATA (EHR.) KIRCHN. + +Valve cymbiform, with gibbous ventral margin; apices truncate; axial area +very narrow, scarcely widened in the middle; striae with fine close puncta. + +Kirkwood Pond, N. J. + +Pl. 18, Fig. 4. + + +CYMBELLA MEXICANA (EHR.) A. S. + +Valve broad, with gibbous ventral margin and sub-rostrate, truncate apices; +median line with reflexed terminal fissures; striae with coarse puncta; a +large punctum occurs in the centre of the central area. + +Blue clay. + +Pl. 18, Fig. 5. + + +CYMBELLA TUMIDA (BREB.) V. H. + +Valve cymbiform, with gibbous ventral margin and abruptly rostrate ends; +median line arcuate; axial area narrow; central area large, orbicular; +below the central nodule is a punctum; striae punctate. + +Crum Creek. + +Pl. 18, Fig. 7. + + +SECTION 3.--ENCYONEMA. FRUSTULES IN TUBES + +CYMBELLA VENTRICOSA KUETZ. + +Valve lunate, with straight or slightly gibbous ventral margin; axial area +indistinct; median line straight or nearly so; striae punctate. + +Very common, but extremely variable. The ventral margin is sometimes +straight and sometimes quite gibbous. + +Pl. 18, Figs. 14, 22; Pl. 38, Fig. 16; Pl. 40, Fig. 8. + +{63}C. ventricosa is considered by some authors to be equivalent to C. +affinis var. semicircularis Lagerst., Encyonema prostratum (Berk.) Ralfs, +E. caespitosum Kuetz. and E. auerswaldii Rab. H. L. Smith's Type Slide of +C. ventricosa Ag. is said to equal C. affinis Kuetz., but the specimens +appear to me to be equivalent to C. ventricosa Kuetz. Cleve unites many +forms, including E. caespitosum, under C. ventricosa. + + +CYMBELLA PROSTRATA (BERK.) CL. + +Valve semi-elliptical, obtuse at the apices, which are sometimes prolonged +and turned downwards; median line straight, terminal nodules distant from +the ends; axial area narrow, central area rounded; striae in radiating, +slightly curved lines, indistinctly punctate. + +Common in fresh water; occasional in brackish. + +Pl. 18, Fig. 21 (represents a frequent variation). + + +CYMBELLA PHILADELPHICA N. SP. + +Valve semi-elliptical-lanceolate, with rounded apices; ventral margin +strongly gibbous; terminal nodules distant from the ends; axial area broad, +central area widened on the dorsal side; striae radiate, not curved nor of +unequal length, indistinctly punctate, 10 in 10 [mu] on the dorsal, 8 in 10 +[mu] on the ventral side. L. 86 [mu]. + +This form approaches Encyonema prostratum (Berk.) Ralfs, Schmidt's Atlas, +Pl. 71, Fig. 7, but differs in the striae and the axial and central areas. + +Blue clay of Philadelphia. Rare. + +Pl. 18, Fig. 8. + + +CYMBELLA TRIANGULUM (EHR.) CL. + +Valve semi-elliptical, with acute ends; median line straight; ventral side +half the width of the dorsal, with straight, slightly convex or concave +margin; striae radiate, coarsely punctate. + +_Gloeonema triangulum_ Ehr. + +Baker's Run, Willistown, Pa. + +Pl. 18, Fig. 24. + + +CYMBELLA TURGIDA (GREG.) CL. + +Valve semi-elliptical, with acute ends; ventral margin gibbous; ventral +side half the width of the dorsal; median line straight; terminal fissures +turned downwards; axial area broad; striae radiate, coarsely punctate. + +Baker's Run, Willistown, Pa. + +Pl. 18, Fig. 23. + + +CYMBELLA TURGIDA (GREG.) CL. VAR. ? + +Valve lunate, with gibbous ventral margin; median line straight; terminal +fissures turned downwards near the ends; axial area lanceolate, striae +radiate on the dorsal side, 8 in 10 [mu], punctate, 9 on the ventral side, +closer at the ends where they are convergent. L. 65 [mu]. Not a typical +form. + +Willistown, Pa. + +Pl. 18, Fig. 12. + + +CYMBELLA RHOMBOIDEA N. SP. + +Valve rhomboidal, with acute ends; dorsal part one and a half times the +width of the ventral; median line nearly straight, with terminal fissures +turned downwards near the ends; axial area broad, not widened in the +middle, except slightly on the ventral side; striae {64}radiate, distant in +the middle of the dorsal side where they are 7 in 10 [mu], coarsely +punctate, the puncta in longitudinal lines, 9 in 10 [mu] on the ventral +side, closer at the ends. L. 69 [mu]. + +Baker's Run, Willistown, Pa. + +Pl. 18, Fig. 11. + + +CYMBELLA GRACILIS (RAB.) CL. + +Valve semi-lanceolate, with acute ends; median line nearly straight, with +terminal fissures turned downwards, distant from the ends; axial area +linear; ventral margin straight or slightly gibbous in the middle. + +Hammonton Pond, N. J. + +Pl. 18, Fig. 20. + + +CYMBELLA LACUSTRIS (AG.) CL. + +Valve elliptical-lanceolate, with obtuse ends, nearly symmetrical; median +line straight, terminal fissures distant from the ends; striae radiate in +the middle, convergent at the ends, coarsely lineate. + +Belmar, N. J. + +Pl. 18, Fig. 25. + + +AMPHORA EHR. (1840) + +(amphora, a jar) + +Valves asymmetrical along the longitudinal axis, as in Cymbella, but with +the plane passing through the dorsal and ventral sides of one valve at an +angle with that of the other. As Cleve states, Cymbella and Amphora are +forms of Navicula "with both valves similar and asymmetrical along the +longitudinal axis," and the difference between Cymbella and Amphora is in +the "degree of asymmetry." If, following H. L. Smith's diagrams (Lens, Vol. +2, 1873, p. 66), we assume that the usual form of the valve in Navicula is +elliptical or lanceolate, and the zone view is rectangular, we have in +Cymbella an arcuate median line and a more or less reniform valve, while +the zone view remains rectangular with the valves parallel. Now, if the +valves are asymmetrical along the longitudinal axis, and one side of one +valve is separated from the corresponding side of the opposite valve by a +wider connective zone than is the case on the other side, the transverse +section of the frustule will appear cuneate, as in Amphora, and the +connective zone will be wider on one side than the other. When, therefore, +we examine an entire frustule as it is usually seen, we shall find the two +raphes of the valves in focus at the same time on the ventral side, and, by +changing the focus, the convex sides of the same valves are seen, the +dorsal view with, usually, a wider connective zone. As an illustration, +compare Figs. 5 and 6, on Plate 15, Fig. 6 being the ventral, and Fig. 5 +the dorsal view. + +As Amphorae are epiphytic or parasitic, they are considered, as Cleve +remarks, like Achnanthes and Cocconeis, as "degenerated forms." + +Chromatophores usually single, lying on the ventral connective zone. +Mereschkowsky describes nine forms. + +Cleve divides the genus into a number of groups as follows: + +_Amphora proper._--Connective zone not complex; valves with longitudinal +lines on the dorsal side; coarsely punctate or costate. + +_Diplamphora._--Zone complex; otherwise as in Amphora. + +_Halamphora._--Longitudinal lines absent; frustule elongate, with +protracted ends. + +{65}_Oxyamphora._--Zone complex; longitudinal lines absent; frustule +elliptical; valve lunate, with or without a central stauros; striae +punctate. + +_Amblyamphora._--Zone complex; frustule rectangular; valve lunate; striae +punctate; axial and central areas indistinct. + +_Psammamphora._--Zone not complex; frustule rectangular; central nodule +frequently dilated to a stauros; no axial or central area. + +_Cymbamphora._--Valve semi-lanceolate; median line straight, approximate to +the ventral margin. + + +AMPHORA + +AMPHORA ROBUSTA GREG. + +Frustule elliptical, truncate; valve lunate, with straight ventral margin; +median line biarcuate; ventral side with coarse, radiate striae, 6 in 10 +[mu], on both sides of the median line. + +Along the coast. + +Pl. 15, Fig. 1. + + +AMPHORA PROTEUS GREG. + +Frustule elliptical, truncate; valve lunate, with straight ventral margin; +median line biarcuate; no central area. Striae on the dorsal side not +interrupted, 9 in 10 [mu]. Ventral side striate toward the ends. + +Differs from A. robusta chiefly in size and coarseness of puncta. Extremely +variable in size. + +Common along the coast. + +Pl. 15, Figs. 5, 6, and 19. + + +AMPHORA OVALIS (BREB.) KUETZ. + +Frustule elliptical, truncate; valve lunate; median line biarcuate; striae +on dorsal side 10-16 in 10 [mu]. + +_Var. libyca (Ehr.) Cl._--Central area distinct on the dorsal side. + +_Var. pediculus (Kuetz.) Cl._--Central area and nodule quite distinct. +Striae finer than in var. libyca. + +Common in ponds. Quite variable. + +Pl. 15, Fig. 7. + + +AMPHORA GIGANTEA VAR. FUSCA A. S. + +Frustule elliptical; valve lunate, with straight ventral margin. Axial area +absent on the dorsal side; dorsal striae, 10 in 10 [mu], punctate. Ventral +part hyaline except at the ends, which are obliquely striated, with short, +punctate lines. L. 70-120 [mu]. + +Absecon, N. J. + +Pl. 38, Fig. 1. + + +DIPLAMPHORA + +AMPHORA CRASSA GREG. + +Valve linear-elliptical, with obtuse, incurved ends. Median line biarcuate. +Axial and central areas indistinct on the dorsal side; striae coarsely +punctate, interrupted by a longitudinal line on the dorsal side. + +Along the coast. + +Pl. 15, Fig. 3. + + +{66}AMPHORA AREOLATA GRUN. + +Valve with straight ventral margin; median line straight, approximate to +the ventral margin; axial area indistinct; several longitudinal lines +crossed by apparent costae which alternate with rows of fine puncta. + +Blue clay. Rare. + +Pl. 15, Fig. 11. + + +HALAMPHORA + +AMPHORA COFFAEIFORMIS (AG.) KUETZ. + +Frustule lanceolate, truncate; zone with numerous divisions. Valve arcuate +on the dorsal and nearly straight on the ventral side; ends protracted or +slightly capitate. + +_A. aponina_ Kuetz. + +_A. salina_ Wm. Sm. + +Along the coast. + +Pl. 15, Figs. 8 and 18. + + +OXYAMPHORA + +AMPHORA LINEOLATA EHR. + +Frustule membranaceous, elliptical, truncate, with broad ends. Zone with +numerous divisions. Dorsal part striated transversely; ventral side with +longitudinal lines. + +_A. plicata_ Greg. + +_A. hyalina_ H. L. Smith, Type No. 64. + +Along the coast. + +Pl. 15, Figs. 9 and 10. + + +AMPHORA OSTREARIA BREB. + +Frustule oblong, with rounded angles. Zone with five or more divisions +transversely striated. Central area narrow, biarcuate; central nodule +dilated to a stauros. Valve narrow, with arcuate dorsal and straight +ventral margin, acute at the ends. Striae transverse, finely punctate. + +_A. vitraea_ Cl.; _A. porcellus_ Kitton; _A. quadrata_ Breb.; _A. elegans_ +Greg. Appearance varies according to the position of the valve. + +Along the coast. + +Pl. 15, Figs. 12 and 21. + + +AMPHORA LAEVIS GREG. + +Frustule oblong, hyaline and membranaceous. Valve linear or slightly +arcuate, with ventral margin tumid in the middle; ends obtuse; central +nodule dilated to a stauros; median line very narrow, biarcuate, coinciding +with the dorsal margin at the ends; striae transverse, punctate. + +Blue clay. + +Pl. 15, Fig. 13. + + +AMPHORA ACUTA GREG. + +Valve lunate, with acute ends; ventral margin straight; ventral side very +narrow. Central nodule dilated to a stauros; striae transverse, punctate. + +Along the coast. + +Pl. 15, Fig. 20. + + +{67}AMBLYAMPHORA + +AMPHORA OBTUSA GREG. + +Frustule rectangular. Valve linear, obliquely rounded at the ends, with +arcuate dorsal, and straight ventral, margin; median line biarcuate; +striae, 18-20 in 10 [mu]. + +Along the coast. Common. + +Pl. 15, Fig. 4. + + +PSAMMAMPHORA + +AMPHORA ARENARIA DONK. + +Frustule hyaline, rectangular, slightly tumid in the middle, with rounded +angles. Valve linear with broad ventral side and straight or sinuate +ventral margin. Striae, 24-27 in 10 [mu] (Cleve). + +Common along the coast. + +Pl. 15, Fig. 17. + +The distinction between A. obtusa and A. arenaria is not always evident if +the valves alone are seen. The former has a complex zone, the latter a +simple zone, and the valve has finer striae. Cleve's descriptions and +references in regard to these two forms do not agree with the descriptions +and figures of H. L. Smith, or with the figures of Schmidt. The valves of +most Amphorae are capable of assuming various outlines according to their +position. + + +AMPHORA OCELLATA VAR. CINGULATA CLEVE + +Frustule rectangular. Valve linear, with dorsal margin arcuate and the +ventral margin straight. Central nodule with a stauros on the dorsal side. + +Squan River, N. J. + +Pl. 15, Figs. 14 and 15. + + +CYMBAMPHORA + +AMPHORA ANGUSTA VAR. EULENSTEINII GRUN. + +Valve lanceolate, acute at the ends. Median line straight, approximate to +the margin. Axial area widened on the dorsal side, indistinct on the +ventral; striae punctate. + +_A. eulensteinii_ A. S. + +Common along the coast. + +Pl. 15, Fig. 16. + +On Pl. 40, Figs. 21, 22, and 23, I have attempted, imitating H. L. Smith's +figures (Lens, l.c.), to illustrate the difference in the transverse +sections of Navicula, Cymbella and Amphora. + +Fig. 21 represents the transverse section of a convex Navicula, in which +the valves ecg and fdh are parallel, and the median nodules c and d are +central. + +Fig. 22 is a transverse section of Cymbella in which the valves are nearly +parallel and the median nodules are excentric. The girdles on one side, ea +and af, are narrower than gb and bh on the other side. + +Fig. 23 is a transverse section of an Amphora in which the valves appear in +zone view with the median nodules of both valves on the same side. The +girdles on the ventral side, ea and af, are narrower than gb and bh on the +dorsal side. The girdles on the dorsal side are seldom as broad as gb and +bh, the valve extending over a great part of the dorsal side to g' and h'. + + +{68}AMPHIPRORA EHR. (1843) + +(amphi, on both ends, and prora, a prow) + +Frustule twisted in the longitudinal axis, constricted in the middle; zone +complex, with numerous divisions crossed by fine striae. Valve lanceolate, +acute. The raphe confined within a sigmoid keel or extension of the valve; +the central and terminal nodules indistinct. Striae transverse, punctate, +with coarser striae at the junction of the keel and lower part of the +valve. + +Chromatophores single, with indented border except in A. pulchra, in which +there are two chromatophores with entire borders. + + +AMPHIPRORA ALATA KUETZ. + +Frustule with a row of puncta at the junction line. Valve linear, acute at +the ends. Median line sigmoid. Striae lineate on the lower part of the +valve, punctate on the keel. + +Along the coast. Not common. + +Pl. 14, Fig. 3. + + +AMPHIPRORA PULCHRA BAIL. + +Frustule with sigmoid connective zone. Valve very convex, with sinuate keel +and junction lines evident. In zone view and in valve view, one half of the +frustule, owing to the elevation of the keel, is wider than the other half. +Striae punctate, coarser on the keel. + +Not uncommon along the coast. + +Pl. 14, Figs. 1 and 2. + + +AMPHIPRORA CONSPICUA GREV. + +Valve linear or elliptical, with acute ends. Median line sigmoid, but the +junction lines not evident. Striae lineate, with coarser lines near the +middle. + +Not common. Port Penn, Delaware River. + +Pl. 14, Fig. 4. + + +AMPHIPRORA ORNATA BAIL. + +Frustule membranaceous, constricted in the middle, with well-marked folds +extending from the junction line in both directions. Valve lanceolate, +constricted in the middle and with protracted ends. Keel undulate on the +edge. + +A beautiful, transparent and delicate form, the only fresh-water species in +our locality. + +Delaware Water Gap, Pa. + +Pl. 14, Figs. 6 and 7. + + +AMPHIPRORA PALUDOSA WM. SM. + +Frustule membranaceous, constricted, with truncate ends. Valve linear, with +acute ends. Striae scarcely visible. + +Cape May (Cleve). + +Pl. 14, Fig. 5. + + +TROPIDONEIS CLEVE (1891) + +(tropis, a keel) + +Frustule oblong, constricted in the middle; keel not sigmoid. Axial area +not evident. Striae very fine, punctate, in longitudinal lines. + + +{69}TROPIDONEIS LEPIDOPTERA (GREG.) CLEVE + +Valve with straight, median excentric line. Keel unilateral, projecting +above the median line in zone view; central area small. Transverse striae +finely punctate. As usually seen, the valve is inclined. According to +Karsten there are two chromatophores on the connective zone, each divided +into four parts, each of which contains a large oval pyrenoid. + +_Amphiprora lepidoptera_ Greg. + +Along the coast. + +Pl. 14, Figs. 8 and 9. + + +AURICULA CASTRACANE (1873) + +(auricula, the ear, the shape of the valve) + +Frustule globose. Valve reniform or cymbiform, elevated into a keel which +is not sigmoid. Median line biarcuate. Differs from Amphiprora in not +having a sigmoid keel. + + +AURICULA MUCRONATA (H. L. SMITH) PERAGALLO + +In zone view, the median line deeply bisects the longitudinal axis, ending +in a mucronate central nodule. Connective zone complex. Valve very complex, +with ventral margin nearly straight and raphe excentric. Central nodule +near the margin, terminal nodules small. Striae, 35-40 in 10 [mu] (Cleve). +Chromatophore single, on the ventral part. + +_Amphora mucronata_ H. L. Smith. + +_Amphora (?) insecta_ Grun. + +_Auricula insecta_ (Grun.) Cleve. + +"A rare and very curious pelagic species" (Peragallo, Diat. Villefranche). + +Prof. H. L. Smith included this form in his first century of "Species +Typicae Diatomacearum," which was issued prior to 1876, the date of +publication, in Schmidt's Atlas, of Amphora insecta Grun. + +Atlantic City, N. J. Rare. + +Pl. 15, Fig. 2. + + +SCOLIOTROPIS CLEVE (1894) + +(scolios, twisted, and tropis, a keel) + +Frustule linear, oblong. Median line sigmoid near the ends. Valve with +transverse costae alternating with two intermediate rows of puncta in +oblique lines. + + +SCOLIOTROPIS LATESTRIATA VAR. AMPHORA CLEVE + +Valve asymmetrical, with the median line curved. Frustule sub-acute at the +ends. Median lines not on the same side of each valve of the frustule. + +Abundant at Cape May, N. J. Not common elsewhere. + +Pl. 14, Figs. 10 and 11. + + +GOMPHONEIS CLEVE (1894) + +(gomphos, a peg, and neis (naus)) + +Valve elongated, asymmetrical to the transverse axis; axial area narrow; +central area rounded, stigmatic; striae radiating, costae alternating with +double rows of fine puncta. An indistinct, longitudinal line near the +border. + +Chromatophores and conjugation have not been determined. + + +{70}GOMPHONEIS HERCULANEUM (EHR.) CL. + +Valve clavate, with rounded apex; costae, 13 in 10 [mu], alternating with +double rows of fine puncta, 22 in 10 [mu], in oblique rows; axial area +narrow, central area rounded, with one stigma. + +_Gomphonema capitatum_ Ehr var. _herculaneum_ Ehr., H. L. S., Type Slide +No. 177. + +Common in the blue clay. + +Pl. 19, Fig. 2. + +Pl. 38, Fig. 15, zone view of young frustule. + + +GOMPHONEIS MAMILLA (EHR.) CL. + +Valve lanceolate, with rounded apex and base; striae costate, 10 in 10 +[mu], alternating with double rows of fine puncta; axial area linear, +sometimes oblique, central area small, with one or more stigmas. + +Blue clay. Rare. + +Pl. 19, Fig. 1. + +In one frustule I noticed one valve with one stigma and the other with four +stigmas. + +The difference between G. mamilla and G. elegans is not very great. In the +latter the central area is larger and the longitudinal lines not so near to +the margin. The stigmas form a circlet. There appears to be a coincidence +in the relation of Gomphoneis to Gomphonema, and that of the true +Achnanthes to the group described by Cleve under Achnanthidium. In +Gomphoneis and Achnanthes the striation is both costate and punctate while +in Gomphonema and Achnanthidium the striation is punctate only. + + +GOMPHONEMA AG. (1824) + +(gomphos, a peg, and nema, a filament) + +Valve elongated, asymmetrical with respect to the transverse axis; striae +transverse, usually radiate, punctate. + +Chromatophore band single, the middle lying on one zone. + +In conjugation, according to Thwaites and Pfitzer, from two mother cells, +which do not form a positive union, two auxospores are developed parallel +to the original frustules. In Plate 19, Fig. 19, I have drawn a +representation of the auxospore formation as I have frequently observed it +in a gathering sent me by Mr. T. C. Palmer, containing G. angustatum, a +common species in this locality. The sagittal plane of the valve of the +auxospore is at right angles to the plane of the valve of the mother cell. +Two valves of one of the mother cells are seen separated, one on each side +of the auxospore which is nearly twice the length of the original +frustules. The two valves of the other mother cell are not shown as they +are not usually found closely united. In the figure one valve alone of the +auxospore is seen, the opposite valve not being in focus. The valves of the +auxospore are usually more or less arcuate, as in Cymbella, to which the +genus is closely allied. + +Grunow divides Gomphonema into two groups, Asymmetricae and Symmetricae, +according to the presence or absence of stigmas. Cleve suggests Stigmaticae +and Astigmaticae as more suitable in order to agree with the Cymbellae. The +Stigmaticae are found chiefly in fresh water, sometimes in brackish. All of +the marine forms belong to the Astigmaticae, which, however, include some +common fresh-water forms. Many species of Gomphonema are stipitate, some +occur in gelatinous masses, and others are free. + + +{71}GOMPHONEMA MONTANUM SCHUM. + +Valve slightly biconstricted, with obtuse apex and basis, somewhat cuneate; +axial area linear, widened in the middle unilaterally; stigma, one; striae +about 11 in 10 [mu], more distant in the middle, punctate. + +_Gomphonema subclavatum_ var. _montana_ (Schum.) Cl. + +Pavonia, N. J., artesian well. Rare. + +Pl. 19, Fig. 3. + + +GOMPHONEMA GEMINATUM LYNG. + +Valve biconstricted, with large, rounded, sub-truncate apex and broad, +sub-truncate basis; striae, 9 in 10 [mu], radiate in the middle, +alternately longer and shorter, transverse at the basis and near the apex +where they again radiate, coarsely punctate, puncta, 12 in 10 [mu]. Axial +area linear; central area rounded, with several large stigmas in a +longitudinal row; terminal fissures hook-shaped. + +Blue clay. + +Pl. 19, Fig. 4. + + +GOMPHONEMA LANCEOLATUM VAR. INSIGNIS (GREG.) CL. + +Valve lanceolate; axial area narrow; central area unilateral with one +stigma; striae with coarse and distant puncta. + +Common and variable. + +_Gomphonema insigne_ Greg. + +Pl. 19, Figs. 6 and 12. + +Fig. 12 shows a unilateral central area. Fig. 6 is more clavate in outline +with small central area. In both forms the coarse puncta are in distinct +longitudinal lines in the middle. + + +GOMPHONEMA ACUMINATUM VAR. TURRIS (EHR.) CL.? + +Valve clavate, with cuneate, acute apex; axial area distinct; central area +unilateral with one stigma. + +Blue clay. + +Pl. 19, Fig. 11. + + +GOMPHONEMA ACUMINATUM VAR. TURRIS (EHR.) CL. + +Valve clavate, with cuneate apiculate apex and narrow basis; axial area +narrow, with a unilateral central space; stigma opposite the short striae; +striae more radiate in the upper part, distant in the middle. + +Smith's Island, Delaware River. + +Pl. 19, Fig. 5. + + +GOMPHONEMA ACUMINATUM VAR. CORONATA (EHR.) CL. + +Valve twice constricted, with broad, cuneate apex; striae radiate in the +middle, convergent near the apex and radiate at the apex. Variable in size +and outline. + +Blue clay. Fresh water. Common. + +Pl. 19, Fig. 7. + + +GOMPHONEMA ACUMINATUM VAR. TRIGONOCEPHALA (EHR.) CL. + +Valve broad, with cuneate apex; axial area narrow; central area unilateral +with one stigma. + +Pavonia, N. J., artesian well. + +Pl. 19, Fig. 20. + + +{72}GOMPHONEMA CONSTRICTUM EHR. + +Valve clavate, constricted beneath the abruptly rounded apex, gibbous in +the middle, striae alternately longer and shorter; axial area narrow, +central area unilateral, with one stigma. + +Common in fresh water. + +Pl. 19, Fig. 8. + + +GOMPHONEMA SPHAEROPHORUM EHR. + +Valve clavate, with capitate or rostrate-capitate apex and narrow basis; +axial area very narrow; central area small, unilateral, with one stigma. + +Common in fresh water. + +Pl. 19, Figs. 9 and 10. Fig. 10 appears to be a transitional form having a +more distinct axial area and rostrate apex. + + +GOMPHONEMA AUGUR EHR. + +Valve broadly clavate, truncate and apiculate at the apex; basis sub-acute; +axial area distinct; central area small, unilateral with one stigma; striae +with distant puncta. + +Blue clay. Willistown, Pa. + +Pl. 19, Fig. 21. + + +GOMPHONEMA INTRICATUM KUETZ. + +Valve narrow, lanceolate, slightly gibbous in the middle; axial area +distinct; central area transverse with one stigma; striae parallel. Quite +variable. + +Common in fresh water. + +Pl. 19, Fig. 14. + + +GOMPHONEMA ANGUSTATUM KUETZ. + +Valve lanceolate, with sub-rostrate apex and basis; axial area indistinct; +central area unilateral, with one small stigma; striae slightly radiate, +indistinctly punctate. + +Very common in fresh water. + +Pl. 19, Figs. 18 and 19. + +Fig. 19, as stated above, represents the formation of an auxospore. + + +GOMPHONEMA AEQUALE GREG. + +Valve linear-lanceolate, nearly symmetrical, with capitate apex and basis; +axial area narrow; central area unilateral, with one stigma; striae radiate +in the middle, slightly convergent at the ends. + +_Gomphonema intricatum var. aequale_ (Greg.) Cl. + +Blue clay. Not common. + +Pl. 19, Fig. 15. + + +GOMPHONEMA SARCOPHAGUS GREG. + +Valve linear, irregular in outline, with rounded apex and basis; axial area +distinct; central area small, unilateral, with one stigma; striae irregular +with coarse, distinct puncta. + +Occasional in fresh water. + +Pl. 19, Fig. 16. + + +GOMPHONEMA CAPITATUM EHR. + +Valve clavate, broad at the sub-truncate apex and slightly constricted, or +with parallel margins; axial area linear, central area stellate, with one +stigma; striae in the middle alternately longer and shorter. + +Blue clay. + +Pl. 19, Fig. 22. + + +{73}GOMPHONEMA PARVULUM VAR. MICROPUS (KUETZ.) CL. + +Valve clavate, with rounded apex and basis; axial area indistinct; central +area unilateral, with a small stigma; striae distant in the middle. + +Common. + +Pl. 19, Fig. 17. + + +GOMPHONEMA VENTRICOSUM GREG. + +Valve clavate, with broad apex and produced, rounded basis; axial area +narrow, widened in the middle; stigma one; striae distant in the middle, +finely punctate. + +Blue clay. + +Pl. 19, Fig. 13. + + +GOMPHONEMA OLIVACEUM LYNG. + +Valve clavate, with broad apex and narrow basis; axial area very narrow; +central area irregular, without stigma; striae radiate, finely punctate. + +Very common. + +Pl. 19, Fig. 23. + + +GOMPHONEMA BRASILIENSE VAR. DEMERARAE GRUN.? + +Valve lanceolate, with sub-cuneate apex and narrowed basis; axial area +lanceolate, broad; no stigma; median fissures remote; striae parallel, 12 +in 10 [mu], punctate, the puncta obsolescent, small or interrupted. + +Willistown, Pa. Rare. + +Pl. 19, Fig. 24. + + +PLEUROSIGMA WM. SM. (1852) + +(pleura, a side, and sigma, the letter s) + +Valve lanceolate, sigmoid; axial area very narrow, central area small; +striae punctate, in transverse and oblique lines. + +Cleve divides the forms usually known as Pleurosigma into two genera, +Pleurosigma and Gyrosigma. Pleurosigma includes all forms having oblique +rows of puncta, while Gyrosigma includes all having longitudinal rows. Both +have transverse striae. The former consists entirely of marine species, +while in the latter the species are found in fresh, brackish and salt +water. + +The endochrome in Pleurosigma, according to Mueller, consists of two bands +which differ in the median part of each valve. Mereschkowsky says that the +endochrome is so divided as to form four bands, two on each valve, that +their position is different in different species, and that they are not the +same on valves of the same frustule. + +Cleve prefers to classify the species of Pleurosigma and Gyrosigma in +accordance with the outline of the valve and the flexure of the median +line. I shall, however, retain the method used by Peragallo and Grunow and +arrange the forms according to the striation. + + +(1) OBLIQUE STRIAE ABOUT 90 DEGREES, MORE DISTINCT THAN THE TRANSVERSE + +PLEUROSIGMA FORMOSUM WM. SM. + +Valve elongated, slender, gently sigmoid, acute at the ends; oblique striae +crossing each other at about 90 degrees; 10-16 in 10 [mu]; transverse +striae, 14-20 in 10 [mu] (Cleve). + +Along the coast. + +Pl. 22, Fig. 5. + + +{74}PLEUROSIGMA OBSCURUM WM. SM. + +Valve linear, not sigmoid, or scarcely so; ends obtuse, subconical; raphe +sigmoid, near the margin at the extremities; transverse and oblique striae +equidistant, 28 in 10 [mu] (Wm. Sm.). + +Abundant at Greenwich Point, Philadelphia. + +Pl. 22, Fig. 4. + + +(2) OBLIQUE STRIAE CLOSER AT THE ENDS + +PLEUROSIGMA NAVICULACEUM BREB. + +Valve lanceolate, slightly sigmoid at the extremities; raphe strongly +sigmoid near the margin at the ends; central nodule large, rounded; oblique +striae, 13-14 in the middle, closer at the ends; transverse striae, 18-20 +in 10 [mu] (Peragallo). + +Long Island Sound. + +Pl. 22, Fig. 6. + + +PLEUROSIGMA VIRGINIACUM H. L. SMITH + +Valve slightly sigmoid, with acute ends; raphe more sigmoid than the valve, +excentric near the ends; oblique striae in different directions at the +centre, 13 in 10 [mu], closer and less distinct at the ends; central nodule +small but prominent because of its thickness, producing by diffraction an +apparently wide area (somewhat exaggerated in the figure). L. 95 [mu], +usually larger. + +_P. affine_ var. _fossilis_ Grun. (Peragallo). + +_P. normanii_ var. _fossilis_ Grun. (Cleve). + +Common in the blue clay. + +Pl. 22, Fig. 8. + + +(3) OBLIQUE STRIAE 60 DEGREES + +PLEUROSIGMA ANGULATUM (QUEKETT) CL. + +Valve rhomboidal, with sub-rostrate or produced ends; central nodule +rhomboidal; raphe central; transverse and oblique striae at an angle of 60 +degrees, equidistant, 18-22 in 10 [mu]. + +_Navicula angulata_ Quekett. + +Along the coast. + +Pl. 22, Fig. 3. + + +PLEUROSIGMA STRIGOSUM WM. SM. + +Valve lanceolate, with sub-acute, somewhat revolute, apices; oblique striae +at an angle of about 60 degrees, otherwise as in angulatum. + +Along the coast. Not common. + +Pl. 22, Fig. 1. + + +PLEUROSIGMA AESTUARII BREB. + +Valve lanceolate, with produced apices; raphe less sigmoid than the valve +and excentric; oblique striae, 19-21 in 10 [mu], at an angle of about 60 +degrees. + +Along the coast. Common. + +Pl. 22, Fig. 7. + + +{75}(4) OBLIQUE STRIAE 60 DEGREES, THE TRANSVERSE MORE DISTANT + +PLEUROSIGMA RIGIDUM WM. SM. + +Valve nearly straight or slightly sigmoid, with obtuse ends; raphe central, +excentric near the ends; oblique striae, 17-21, transverse, 16-19 in 10 +[mu]. (Peragallo). + +New Rochelle, N. Y. + +Pl. 22, Fig. 2 (very near the var. gigantea Grun.) + + +GYROSIGMA HASSALL (1845) + +(gyros, curved, and sigma) + +Valve lanceolate, sigmoid; axial area very narrow, central area small; +striae punctate, in transverse and longitudinal rows. + +Chromatophores two, in long and narrow bands, perforated, differing from +those of Pleurosigma. The elaeoplasts are also arranged differently in the +two genera. (Mereschkowsky, Etudes sur l'Endochrome des Diatomees, Imperial +Academy of Petrograd, 1901, Vol. 11, No. 6, p. 18 et seq.) + +The arrangement is according to Peragallo. + + +(1) LONGITUDINAL STRIAE MORE DISTANT THAN THE TRANSVERSE + +GYROSIGMA HIPPOCAMPUS (EHR.) + +Valve lanceolate, sigmoid, with obtuse ends; raphe nearly central; +transverse striae 15-17, longitudinal, 10-12 in 10 [mu]. + +_Navicula hippocampus_ Ehr. + +_Pleurosigma hippocampus_ (Ehr.) Wm. Sm. + +_Gyrosigma attenuatum_ (Kuetz.) Cl. + +Long Island Sound. + +Pl. 23, Fig. 3. + + +(2) LONGITUDINAL AND TRANSVERSE STRIAE NEARLY EQUAL + +GYROSIGMA BALTICUM (EHR.) CL. + +Valve with margins parallel nearly to the extremities, which are suddenly +unilaterally sub-conical and obtuse; raphe sigmoid; transverse and +longitudinal striae nearly equally distant, 15 in 10 [mu] (Per.). L. +200-360 [mu]. + +_Navicula baltica_ Ehr. + +_Pleurosigma balticum_ (Ehr.) Wm. Sm. + +Common along the coast. + +Pl. 23, Fig. 2. + + +GYROSIGMA PARKERI VAR. STAURONEIOIDES GRUN. + +Valve lanceolate, slightly sigmoid, ends produced into beaks with sub-acute +apices; raphe straight in the middle part; central nodule elliptical; +transverse striae, 21, and longitudinal, 24 in 10 [mu] (Per.). + +An apparent stauros, variable in width, extends to the margin and, in +consequence, the median transverse striae are more evident. L. 75 [mu]. + +Schuylkill River. Rather rare. + +Pl. 23, Fig. 7. + + +{76}GYROSIGMA SIMILE (GRUN.) + +Valve slightly sigmoid, broad, with obtuse ends; raphe sigmoid, nearly +central; transverse striae, 15, longitudinal, 16-17 in 10 [mu] (Per.). + +_Pleurosigma simile_ Grun. + +_Gyrosigma balticum_ var. _similis_ (Grun.) Cl. + +Shark River, N. J. + +Pl. 23, Fig. 4. + + +(3) TRANSVERSE STRIAE MORE DISTANT + +GYROSIGMA ACUMINATUM (KUETZ.) CL. + +Valve sigmoid, tapering to the sub-acute ends; raphe central; transverse +and longitudinal striae nearly equally distant, 17 or 18 in 10 [mu] (Per.). + +_Frustulia acuminata_ Kuetz. + +Port Penn, Delaware River. + +Pl. 23, Fig. 5. + + +GYROSIGMA STRIGILIS (WM. SM.) CL. + +Valve sigmoid, with obtuse ends; raphe doubly sigmoid; axial area rather +wide; transverse striae, 13, and longitudinal, about 16 in 10 [mu]. + +Long Island Sound. Not common. + +Pl. 23, Fig. 1. + + +GYROSIGMA KUETZINGII (GRUN.) CL. + +Valve sigmoid, lanceolate, with sub-acute ends; raphe central, the central +nodule elliptical; transverse striae, 21-23, and longitudinal, 25-26 in 10 +[mu]. + +_Pleurosigma spencerii_ var. _acutiuscula_ Grun. + +_Pleurosigma spencerii_ var. _kuetzingii_ Grun. + +Common in fresh water. + +Pl. 38, Fig. 12. + + +GYROSIGMA SCALPROIDES (RAB.) CL. + +Valve slightly sigmoid, with obtuse ends; raphe nearly straight; central +nodule elliptical; transverse striae, 22, slightly radiate and more distant +in the middle; longitudinal striae, 29 in 10 [mu]. L. 60 [mu]. + +Common in streams. + +Pl. 38, Fig. 9. + +In Pl. 23, Fig. 6 represents a form more sigmoid. + + +GYROSIGMA SPENCERII VAR. NODIFERA GRUN. + +Valve sigmoid, with obtuse ends; raphe central; central nodule obliquely +elongated; transverse striae, 17-18 in 10 [mu], curved in the middle of the +valve, longitudinal striae, 22 in 10 [mu]. L. 150 [mu]. + +Blue clay. + +Pl. 23, Fig. 8. + + +GYROSIGMA PROLONGATUM (WM. SM.) CL. + +Valve narrow, lanceolate, produced into beaks, curved in a contrary +direction; raphe central; transverse striae, 20-21 in 10 [mu], longitudinal +closer. L. 140 [mu]. + +Along the coast, northward. + +Pl. 38, Fig. 13. + +I have not seen any specimens south of New England, but they will probably +occur. + + +{77}(4) STRIAE ALIKE, EXTREMITIES PRODUCED + +GYROSIGMA FASCIOLA (EHR.) CL. + +Valve lanceolate, attenuated into curved beaks turned in opposite +directions; raphe central, straight, except at the beaks; transverse +striae, 22, longitudinal, 24 in 10 [mu] (Per.). + +New York Bay. + +Pl. 23, Fig. 9. + + +FRUSTULIA AG. (1824); em. GRUN. (1865) + +(frustulum, a small piece) + +Valves naviculoid, similar, usually free but sometimes enclosed in +gelatinous tubes or embedded in mucus. Median line between two thickened +ribs. Central and terminal nodules frequently elongated. Surface of valve +with fine puncta in longitudinal and transverse lines appearing hyaline +under medium powers. + +Chromatophores, two, extending along the girdle. They differ from those of +Navicula in being separated from the wall in the middle by a hemispherical +mass of protoplasm. According to Pfitzer, each chromatophore is divided in +the middle, allowing a connection between the hemispherical mass and the +central plasma mass. Schmitz states that the chromatophore is thickened in +the middle and contains a pyrenoid. + +In conjugation, two frustules form two cylindrical bodies which later +become conical and from which are formed the sporangial valves twice the +usual size. + + +FRUSTULIA LEWISIANA (GREV.) DE TONI + +Valve elliptical or linear, with rounded ends; terminal nodules elongated, +at a distance from the ends; striae, 24 in 10 [mu]. + +Port Penn, Delaware River. Along the coast. + +Pl. 17, Fig. 1. + + +FRUSTULIA RHOMBOIDES (EHR.) DE TONI + +Valve lanceolate or rhombic-lanceolate, rounded at the ends; central and +terminal nodules short; striae, 20 in 10 [mu], sometimes coarser. + +Common in fresh water. + +Pl. 17, Fig. 2. + + +FRUSTULIA RHOMBOIDES VAR. AMPHIPLEUROIDES GRUN. + +Valve rhombic-lanceolate; central and terminal nodules elongated; median +line somewhat excentric. + +Blue clay. + +Pl. 17, Fig. 3. + + +FRUSTULIA RHOMBOIDES VAR. SAXONICA (RAB.) DE TONI + +Valve smaller than in rhomboides, with somewhat produced ends, closer +median ribs and rounded central nodule. + +Fresh water. + +Pl. 17, Fig. 6. + + +FRUSTULIA VULGARIS (THWAITES) DE TONI + +Valve elliptical-lanceolate, with rounded or sometimes sub-rostrate ends; +central and terminal nodules slightly elongated; striae delicate, closer at +the ends. Frustules at first in gelatinous tubes. + +_Colletonema vulgaris_ Thwaites. + +Fresh water. + +Pl. 17, Fig. 4. + + +{78}FRUSTULIA INTERPOSITA (LEWIS) DE TONI + +Valve linear-elliptical, rounded at the ends; terminal nodules short. + +_Navicula interposita_ Lewis. + +Along the coast. Port Penn, Delaware River. + +Pl. 17, Fig. 5. + + +AMPHIPLEURA KUETZ. (1844) + +(amphi, on both sides, pleura, a side) + +Frustules free, in gelatinous masses or in tubes. Valve linear-lanceolate; +central nodule narrow, extending half the length of the valve or more, then +forking toward the ends. Terminal nodules prolonged, as in Frustulia, into +a "porte-crayon-shaped" figure. + +Chromatophores two, very short. + + +AMPHIPLEURA PELLUCIDA KUETZ. + +Frustules free or in mucous masses. Valve fusiform; forks about one-fourth +the length of the valve; striae transverse, punctate, 36-40 in 10 [mu] (J. +J. Woodward). + +Occasional in the Delaware River. + +Pl. 17, Fig. 9. + + +AMPHIPLEURA RUTILANS (TRENTEPOHL) CL. + +Frustules enclosed in gelatinous tubes. Valve linear-lanceolate, obtuse at +the ends; forks about one-third the length of the valve; striae, 28 in 10 +[mu]. + +_Conferva rutilans_ Trentepohl. + +_Schizonema dillwynii_ Wm. Sm. + +Abundant at Belmar, N. J. + +Pl. 17, Fig. 10. + +Fig. 11 represents a portion of the gelatinous tube containing frustules. + + +DICTYONEIS CLEVE (1890) + +(dictyon, a net) + +Frustules oblong. Valve lanceolate, constricted in the middle (in our +species); an outer layer finely punctate and an inner layer of +reticulations; the margin of the valve divided into large, quadrate cells. + +The genus Dictyoneis includes species at one time ascribed to Mastogloia +and Navicula. The structure, however, is not like that of either, as the +loculi are attached to the valve and are not separable as in Mastogloia, +and the cell-wall is not like that of any Navicula. + +Cleve remarks that Dictyoneis is found in warm waters. Lewis found one +specimen at Black Rock Harbor, L. I., and one in the Delaware River blue +clay. The specimens here described I found living on the New Jersey coast. + + +DICTYONEIS MARGINATA VAR. TYPICA CLEVE + +Valve panduriform, with cuneate lobes; axial area narrow, linear, scarcely, +or not at all, widened in the middle; terminal fissures in contrary +directions; outer stratum finely punctate, about 25 in 10 [mu], in parallel +striae; inner stratum coarsely reticulated. Four and one-fourth times +longer than broad; marginal cells, 5 in 10 [mu], smaller or obsolescent in +the middle of the valve; cells of the valve in irregular transverse rows, +10-12 in 10 [mu]. L. 93 [mu]. + +_Navicula marginata_ Lewis. + +Absecon, N. J. + +Pl. 20, Fig. 3. + + +{79}DICTYONEIS MARGINATA VAR. COMMUTATA CLEVE + +Valve four and one-half times longer than broad; cells of the valve in +irregular, transverse rows about 11 in 10 [mu]; marginal cells nearly +equal, 6 in 10 [mu]. L. 125 [mu]. + +Absecon, N. J. + +Pl. 20, Fig. 2. + + +DICTYONEIS MARGINATA VAR. MAXIMA N. VAR. + +Valve with cuneate segments; marginal cells, 4 in 10 [mu]; cells of the +valve, 5 in 10 [mu], obsolescent in the middle and smaller; transverse +striae, 25 in 10 [mu]. + +Atlantic Coast. Rare. + +Pl. 20, Fig. 1 (from a specimen found at Colon). + + +TRACHYNEIS CLEVE (1894) + +(trachys, rough, and neis (naus), named from the chief species) + +Valve more or less linear or linear-lanceolate. It appears to be composed +of three strata, one an interior, coarsely dotted, an exterior of fine +puncta in longitudinal striae, scarcely visible, and a median of transverse +anastomosing costae forming irregular alveoli. + +Chromatophores, two or four bands on the zone (Mereschkowsky). + + +TRACHYNEIS ASPERA VAR. INTERMEDIA GRUN. + +Valve linear-elliptic; axial area a stauros widened outward and unilateral. +Striae of the median layer of radiating rows of oblong alveoli. + +Along the coast. Not common. + +Pl. 17, Fig. 15. + +The type form and its numerous varieties are quite ubiquitous. Very large +specimens occur in the Antarctic regions, especially in material from Ross +Island, S. Victoria Land (Shackleton Ant. Exp.). + + +BREBISSONIA GRUN. (1860) + +(named after Alphonse de Brebisson, the distinguished French naturalist) + +Frustules stipitate; valve lanceolate; striae transverse in the middle, +radiate at the ends. Median area narrow, central nodule elongated, terminal +fissures at a distance from the ends. Valve with an outer finely punctate +stratum. + +At one end of one valve in each frustule is found a conspicuous punctum, +the plasma pore of Otto Mueller, through which the frustule is connected +with the gelatinous stipe, analogous to the pore in Diatoma connecting the +zig-zag frustules. + +Chromatophore single, lying on one girdle and passing over to each valve. + + +BREBISSONIA BOECKII (KUETZ.) GRUN. + +Valve lanceolate, with sub-acute apices; striae, 3-4 in 10 [mu], not +reaching the median line. + +Blue clay. Very rare. Common in brackish water at Chestertown, Md. (T. C. +Palmer) + +Pl. 17, Fig. 7. + + +{80}BREBISSONIA PALMERII, N. SP. + +Valve rhombic-lanceolate, with cuneate ends and produced apices. Central +nodule more elongate and terminal fissures further from the ends than in B. +boeckii. + +Pavonia, N. J. (artesian well, depth of 40 ft.). Rare. + +Pl. 17, Fig. 8. + +I take pleasure in naming this species after Mr. T. Chalkley Palmer, of +Media, Pa., the author of numerous papers on the Diatomaceae. + +Lewis partly describes a similar form, which he does not name, as a species +of Navicula found in the blue clay at Kaighn's Point, N. J. (Lewis, "New +and Intermediate Forms," etc., p. 15, Pl. 1, Fig. 8.) + + +ANOMOEONEIS PFITZER (1871) + +(anomoios, unlike, and neis (naus), a boat) + +Valve lanceolate, axial area narrow, central area widened; transverse +striae punctate, the puncta in longitudinal rows or interrupted by blank +lines. + +A single chromatophore lies along one of the girdle sides and extends over +the valves, each of the two parts being deeply notched or slit at the ends. +According to Schmitz there are two pyrenoids, but Heinzerling thinks there +is but one. + +Cleve considers this genus not well founded, as it is based upon the cell +contents of but one species, the structure of the other species not being +known. As the forms here described are easily recognized by the interrupted +puncta, the genus is, at least, convenient. + + +ANOMOEONEIS SPHAEROPHORA (KUETZ.) CL. + +Valve elliptic-lanceolate, ends rostrate-capitate. Axial area narrow, +central area rounded, larger on one side of the median line than the other. +Striae very slightly radiate, 16 in 10 [mu], punctate, the puncta +interrupted by longitudinal blank lines. + +Pfitzer states that the central plasma mass is unequal on the two sides. + +_Navicula sphaerophora_ Kuetz. + +Fresh and brackish water. Not common. + +Pl. 40, Fig. 2. + + +ANOMOEONEIS SERIANS (BREB.) CL. + +Valve lanceolate, acute; axial area lanceolate; striae, 24 in 10 [mu]; +puncta elongate. + +Not common in this locality, but abundant northwards; fossil in the peat +deposits of New England. + +May's Landing, N. J. + +Pl. 17, Fig. 12. + +Forma minor--Valve rhombic-lanceolate, smaller than the type. + +May's Landing, N. J. + +Pl. 17, Fig. 13. + + +ANOMOEONEIS FOLLIS (EHR.) CL. + +Valve rhomboid, tumid in the middle and obtuse at the produced ends. +Central area lanceolate; striae radiate in the middle, transverse at the +ends. + +_Navicula follis_ Ehr. + +_Navicula trochus_ Kuetz. + +{81}Reported by Lewis as very rare in the blue clay of the Delaware River. +I have not seen it in this locality. The figure is drawn from a specimen in +the W. Bridgewater, Mass., deposit. + +Pl. 17, Fig. 14. + + +CALONEIS CLEVE (1894) + +(calos, beautiful) + +Valve convex, linear or lanceolate in general outline, with transverse, +smooth or finely punctate striae crossed by one or more longitudinal lines. + +Endochrome of two chromatophores lying one on each valve, entire in some +species and deeply cleft in others. + + +CALONEIS LIBER (WM. SM.) CL. + +Valve linear, with parallel margins and rounded ends; axial area narrow, +central area orbicular; striae transverse in the middle, slightly divergent +at the ends, 16 in 10 [mu]; terminal fissures slightly curved in the same +direction; longitudinal line median. L. 82 [mu]. + +Atlantic coast, chiefly southward. + +Pl. 40, Fig. 1. + + +CALONEIS SILICULA (EHR.) CL. + +Valve linear, gibbous in the middle, with broad sub-cuneate ends; axial +area narrow, central area rounded; longitudinal line marginal; striae +parallel or nearly so, 16 to 18 in 10 [mu]. + +_Navicula silicula_ Ehr. + +_Navicula limosa_ Donk. + +Blue clay. + +Pl. 21, Fig. 3 (var. genuina Cl.). + + +CALONEIS SILICULA VAR. INFLATA (GRUN.) CL. + +Valve gibbous in the middle, with rounded ends; central area elliptical. + +Schuylkill River. + +Pl. 21, Fig. 4. + +C. silicula may be recognized by its yellow color when dry. Its varieties +are extremely numerous. + + +CALONEIS TRINODIS (LEWIS) + +Valve divided into three segments of equal width; ends cuneate and usually +produced; axial area elliptical with a lunate marking on each side; striae +radiate in the middle, elsewhere parallel, about 20 in 10 [mu], finely +punctate; longitudinal line marginal, scarcely visible; the striae become +fainter toward the axial area. + +Occasional in streams and in the blue clay. Abundant in a water-trough at +Ashbourne, Pa. + +Pl. 21, Fig. 8. + +I have retained Lewis' name as specific. Lewis, wrongly, I think, ascribes +his species to _Navicula trinodis_ Wm. Sm., which is not figured by Smith, +but is illustrated by Van Heurck (Syn. Pl. 14, Fig. 31a), and is named by +Cleve _Navicula contenta_ var. _biceps_ Arnott. {82}De Toni includes Lewis' +name under _Rhoiconeis trinodis_ (Wm. Sm.) Grun. Rhoiconeis is +achnanthiform, with frustules arcuate, and the species is named by Cleve +_Achnanthes trinodis_ (Arnott). _Caloneis schumanniana_ (Grun.) Cl., to +which as a variety Cleve unites Lewis' form, appears to resemble it only in +the lunate marks. + +Fig. 9 represents a single specimen found in the Pavonia deposit and which +I believe to be an abnormal form of C. trinodis, differing only in the +degree of inflation and in the larger central area. + +_Navicula trinodis_ var. _inflata_ Schultze, from Staten Island, is the +same form figured by Lewis, who states that certain specimens have produced +apices. + + +CALONEIS PERMAGNA (BAIL.) CL. + +Valve lanceolate, with produced apices; median line nearly straight; axial +area lanceolate, irregular or slightly unilateral, about half the width of +the valve; striae, 9 in 10 [mu], radiate and indistinctly punctate; +longitudinal lines double. L. 100-200 [mu]. + +_Pinnularia permagna_ Bail. + +Common in brackish water. + +Pl. 21, Fig. 1. + + +CALONEIS PERMAGNA VAR. LEWISIANA N. VAR. + +Valve lanceolate, with undulating sides and sub-cuneate apices; axial area +less than one-third the width of the valve; striae radiate, 12 in 10 [mu], +indistinctly punctate; longitudinal lines double, closer together than in +the type. L. 140 [mu]. + +Lewis illustrates this variety in "New and Rare Species," Pl. 2, Fig. 11, +and states that it is probably Navicula esox Kuetzing. This is an error, as +Kuetzing's species is Pinnularia esox Ehr., a form near P. major. + +Rather common in the Delaware River. + +Pl. 21, Fig. 2. + + +CALONEIS FORMOSA (GREG.) CL. + +Valve lanceolate, with sub-cuneate apices; axial area one-fourth to +one-fifth the width of the valve, somewhat unilateral, dilated in the +middle; striae, 12-14 in 10 [mu] radiate, punctate; longitudinal lines +double, distinct. Variable in size and outline. + +Abundant along the shores of the Delaware River. + +Pl. 21, Fig. 18. + + +CALONEIS BREVIS VAR. VEXANS (GRUN.) CL. + +Valve elliptical-lanceolate; apices obtuse; median fissures distant; axial +area narrow; central area large, orbicular; longitudinal lines close +together, median. + +Shark River, N. J. + +Pl. 21, Fig. 5. + + +CALONEIS WARDII CL. + +Valve linear, ends cuneate; axial area linear; central area dilated to a +stauros reaching the margin; striae parallel, radiate at the ends, 18 in 10 +[mu]; longitudinal lines marginal. + +Not uncommon in the Delaware River. + +Pl. 21, Figs. 6 and 7. + + +{83}CALONEIS POWELLII (LEWIS) CL. + +Valve linear, with cuneate ends; axial area linear; central area large, +quadrate, united to the wide longitudinal lines; striae parallel, smooth, 8 +in 10 [mu]. + +Long Island (Lewis); Smith's Island, Delaware River. + +Pl. 21, Fig. 10. + + +NEIDIUM PFITZER (1871) + +(neidion, dim. of naus, a boat) + +Valve linear or lanceolate; median fissures turned in opposite directions, +terminal fissures appearing bifurcate (?); striae transverse, usually +oblique, finely punctate, crossed by one or several longitudinal blank +lines. + +Chromatophores, two, lying on the girdle side, in cell division each +forming a partially divided pair. A large pyrenoid is said to be found in +the middle of each chromatophore, but Mereschkowsky states that the +pyrenoids are absent, but that in N. affine four elaeoplasts are always +seen in the centre of the frustule. + +A genus easily recognized by the peculiar terminal and median fissures and +by the yellowish or brownish color of the valves when dry, darker than in +Caloneis. + + +NEIDIUM AFFINE (EHR.) PFITZER + +Valve linear, with protracted, sub-rostrate or capitate ends. + +_Navicula affinis_ Ehr. + + +NEIDIUM AFFINE VAR. GENUINA FORMA MAXIMA CL. + +Striae, 14 in 10 [mu], punctate, oblique in the middle, convergent at the +ends; puncta, 15 in 10 [mu]. L. 238 [mu]. + +Pensauken, N. J. (artesian well). + +Pl. 21, Fig. 11. + +Var. genuina forma minor Cl.--L. 26 [mu]; striae, 24 in 10 [mu]. + +Brandywine Creek. + +Pl. 21, Fig. 12. + + +NEIDIUM AFFINE VAR. AMPHIRHYNCUS (EHR.) CL. + +Valve linear, with protracted capitate ends; striae transverse, interrupted +by several longitudinal lines. + +Willistown, Pa. + +Pl. 21, Fig. 13. + + +NEIDIUM AMPHIGOMPHUS (EHR.) PFITZER + +Valve with parallel margins and cuneate ends; striae transverse, +interrupted by several longitudinal lines; central area widened +transversely. + +_Navicula amphigomphus_ Ehr. + +Wissahickon. + +Pl. 21, Fig. 14. + + +NEIDIUM PRODUCTUM (WM. SM.) CL. + +Valve linear, elongate, with capitate apices; striae slightly oblique; +longitudinal lines marginal; axial area very narrow, central area small. + +_Navicula producta_ Wm. Sm. + +Newtown Square. + +Pl. 21, Fig. 16. + + +{84}NEIDIUM IRIDIS (EHR.) CL. + +Valve linear or lanceolate-elliptical, with sub-cuneate or rounded ends; +striae oblique, about 18 in 10 [mu]; central area orbicular. + +_Navicula iridis_ Ehr. + +_Navicula firma_ Kuetz. + +Willistown, Pa.; Middletown, Delaware Co., Pa. (Palmer). + +Pl. 21, Fig. 17. + +The form here figured is probably the variety ampliata (Ehr.) Cl. with less +acute apices and more elliptical outline. The species occurs in many +variations, the larger being found northward, especially in the peat +deposits of New England. + + +NEIDIUM HITCHCOCKII (EHR.) CL. + +Valve linear, with triundulate margin and cuneate ends; striae transverse, +oblique. + +_Navicula hitchcockii_ Ehr. + +Pavonia, N. J. (artesian well); Kirkwood Pond, N. J. + +Pl. 21, Fig. 15. + + +DIPLONEIS EHR. (1840) + +(diplos, double) + +Valve elliptical or panduriform; median line enclosed in strongly siliceous +horns corresponding to the lyre-shaped areas of Navicula lyra but never +punctate; central nodule, quadrate; valve costate, or striate, or both; +between the horns and the outer part are thinner spaces or sulci, and, in +some species, outside of the sulci are narrow spaces known as lunulae. + +Chromatophores, two, upon the girdle or the valves. Pyrenoids have been +found in one species only, D. interrupta. + + +DIPLONEIS ELLIPTICA (KUETZ.) CL. + +Valve elliptical; central nodule large; sulci narrow, curved, close to the +horns; striae punctate, in rows radiating more and more toward the ends. +Variable in size and in the coarseness of puncta which are from 10 to 13 in +10 [mu] (Cleve). + +Cleve describes D. ovalis Hilse as having the central nodule rounded, but +otherwise about the same as D. elliptica, and as equivalent to Navicula +ovalis A. Schmidt (Atlas, Pl. 7, Figs. 33 to 36). + +Very common in fresh water and occasional in brackish. + +Pl. 20, Fig. 14. + + +DIPLONEIS SMITHII (BREB.) CL. + +Valve elliptical; central nodule not broad; furrows evenly curved on the +outer edge, crossed by costae and double oblique rows of alveoli. Variable +in size and in the curvature of the furrows. + +Cleve forms a new species, D. major, of the large form figured by Schmidt +(Atlas, Pl. 7, Figs. 18, 19, 21 and 22), stating that the structure is much +coarser and the form is larger with broad furrows. In the specimen here +figured the size is median and the furrows are as in D. major. + +Marine and brackish. Common. + +Pl. 20, Fig. 17. + + +{85}DIPLONEIS CRABRO VAR. PANDURA (BREB.) CL. + +Valve constricted, segments tongue-shaped; central nodule small; horns +narrow, nearly parallel, with a row of large puncta; costae, 4 in 10 [mu], +convergent in the middle, radiating at the ends, alternating with a double +row of puncta, 11 in 10 [mu]. + +Pavonia, N. J. (artesian well). + +Pl. 20, Fig. 4. + + +DIPLONEIS CRABRO VAR. EXPLETA (A. S.) CL. + +Valve slightly constricted, segments tongue-shaped; costae robust, 5 or 6 +in 10 [mu], alternating with double rows of rather coarse puncta. L. 56 +[mu]. + +Port Penn, Delaware River. + +Pl. 20, Fig. 15. + + +DIPLONEIS CRABRO VAR. PANDURELLA CL.? + +Valve constricted, the lobes elliptical; central nodule large, with horns +parallel in the middle, convergent at the ends; furrows wide, with faint +costae; no lunula; costae parallel in the middle, radiate at the ends, 9 in +10 [mu], alternating with very fine double rows of puncta (not shown in the +figure). L. 65 [mu]. + +Blue clay. + +Pl. 20, Fig. 13. + + +DIPLONEIS CRABRO VAR.? + +Valve constricted, segments elliptical; costae, 8 in 10 [mu], converging in +the middle, radiating at the ends; horns narrow; furrows wide, costate; +lunulae indistinct. L. 75 [mu]. + +Resembles var. pandurella except in the convergence of the costae and in +the lunula. + +Squan River. Marine. + +Pl. 20, Fig. 9. + + +DIPLONEIS FUSCA VAR. DELICATA (A. S.) CL. + +Valve elliptical; furrows broad, crossed with rows of faint costae and +alveoli; costae, 6 or 7 in 10 [mu]; alveoli, 10 in 10 [mu], in short, +irregular, longitudinal rows. L. 84 [mu]. + +Port Penn, Delaware River. + +Pl. 20, Fig. 11. + + +DIPLONEIS GRUENDLERI (A. S.) CL. + +Valve constricted, segments tongue-shaped, often unequal; horns broad, +divergent in the middle; furrows narrow; costae transverse, crossed by from +3 to 7 longitudinal costae, interrupted in the middle at the border. + +Blue clay. + +Pl. 20, Figs. 7 and 8. + + +DIPLONEIS PUELLA (SCHUM.) CL. + +Valve elliptical, sometimes orbicular; furrows very narrow; striae, 20 in +10 [mu], indistinct. L. 15 [mu]. + +_Diploneis elliptica_ var. _minutissima_ Grun. + +Shark River, N. J. Brackish. + +Pl. 20, Fig. 12. + + +DIPLONEIS EXCENTRICA, N. SP. + +Valve elliptical; central nodule quadrate; furrows of the same width +throughout, nearly parallel; costae radiating toward the ends, 10 in 10 +[mu], indistinct on the furrows, alternating with alveoli, 7 in 10 [mu], in +irregular, longitudinal lines. One side of the valve is one and a half +times the width of the other. L. 49 [mu]. + +{86}I can find neither description nor figure of any species to which I can +ascribe this form. It approaches D. elliptica. The alveoli are quite +distinct and distant from each other. + +Brackish water. Very abundant in a gathering from Squan River, N. J. + +Pl. 20, Fig. 10. + + +DIPLONEIS OCULATA (BREB.) CL. + +Valve elliptical; striae radiate at the ends, about 20 in 10 [mu], coarsely +punctate. L. 23 [mu]. + +Fresh water. + +Pl. 26, Fig. 7. + +The figure is drawn from Brebisson's original material in H. L. Smith's +Type Slide No. 299. + +_Navicula oculata_ Breb. + +Reported from New Jersey. I have not seen this species in this locality. +Navicula oculata, referred to by Kain as occurring in Shark River, is not +this form. + + +DIPLONEIS GEMMATA (GREV.) CL. + +Valve oblong-linear, with cuneate ends and parallel or slightly concave +sides; central nodule large; horns parallel; furrows about one-third the +width of the valve. Costae about 5 in 10 [mu], alternating with double rows +of fine puncta; short costae occur along the borders of the horns. + +Port Penn, Delaware River. + +Pl. 20, Fig. 16. + + +DIPLONEIS CAMPYLODISCUS (GRUN.) CL. + +Valve suborbicular; central nodule quadrate; horns divergent; costae, 6 in +10 [mu], alternating with double rows of alveoli; furrows broad, costate +near the horns. + +Differs from Cleve's description in having 6, instead of 4, costae in 10 +[mu]. + +Pensauken, N. J. (artesian well). Rare. + +Pl. 20, Fig. 6. + + +MASTOGLOIA THWAITES (1856) + +(mastos, a breast, and gloios, gelatinous, referring to the "mamillate +cushion" in which the frustules are often immersed) + +Frustule rectangular. Valves similar, naviculoid. Central and axial areas +usually narrow or indistinct; striae punctate, parallel in the middle. On +each side, between the valve and the zone, is a septate plate. + + +ANALYSIS OF SPECIES + + + Striae interrupted by a hyaline furrow on each side of + the median line kinsmanii + + Striae not interrupted: + + Loculi, five, or less exigua + + more than five, equal, ending at distance from + the ends smithii + + ending near the ends, distinct lanceolata + + indistinct elegans + + very numerous apiculata + + unequal angulata + +{87}Karsten states that there are two chromatophores, each of which extends +from the middle of one valve to the end and down the middle of the other +valve. Mereschkowsky says, however, that there are four plates or +chromatophores, sometimes on the valve, sometimes on the zone, according to +the species, and that two long pyrenoids unite the two opposite +chromatophores. + + +MASTOGLOIA KINSMANII LEWIS + +Valve lanceolate-elliptical, with sub-rostrate ends; loculi more numerous +than in M. angulata but less than in M. apiculata, the middle ones larger. +Median line with a sulcus on each side; central area quadrate. + +_Mastogloia braunii_ Grun. (According to Cleve). + +Atlantic City. + +Pl. 17, Fig. 16. + + +MASTOGLOIA EXIGUA LEWIS + +Valve elliptical- or linear-lanceolate; loculi, 2-5, usually 3, larger in +the middle and rounded; central space small; striae, 20-24 in 10 [mu]. + +Along the coast. + +Pl. 17, Fig. 24. + + +MASTOGLOIA SMITHII THWAITES + +Valve lanceolate, sub-rostrate; loculi forming a wide band ending at a +distance from the ends; striae transverse, with puncta forming longitudinal +rows; central area rounded or transversely elliptical. + +Along the coast. + +Pl. 17, Fig. 19. + + +MASTOGLOIA LANCEOLATA THWAITES + +Valve lanceolate, with sub-rostrate apices; loculi very numerous; median +and central areas indistinct; striae, 19 in 10 [mu], punctate, convergent +at the ends. + +Along the coast. + +Pl. 17, Fig. 18. + + +MASTOGLOIA ELEGANS LEWIS + +Valve lanceolate, acute; loculi indistinct or rudimentary, extending to the +ends; central area apparently quadrate, sometimes indistinct; puncta +distinct, 15 in 10 [mu], in transverse and longitudinal rows. + +Along the coast. Common. + +Pl. 17, Fig. 20. + + +MASTOGLOIA APICULATA WM. SM. + +Valve elliptical-lanceolate, sometimes with slightly produced apices; +median line between two ribs; central space very small; loculi numerous; +puncta in slightly radiating rows and in longitudinal lines. + +Along the coast. + +Pl. 17, Figs. 21, 22, 23. + + +MASTOGLOIA ANGULATA LEWIS + +Valve elliptical, with produced apices; loculi usually less than 12, +unequal, the larger in the middle; striae, 12 in 10 [mu], puncta in +decussating rows. "Differs from apiculata in its more broadly elliptical +shape, the smaller number of its loculi and the angular character of its +striation" (Lewis). + +{88}Considered by Cleve as synonymous with M. apiculata Grun., not Wm. +Smith, and by De Toni as synonymous with M. apiculata Wm. Sm. In any case, +M. angulata Lewis is not the same as M. apiculata Wm. Sm., the loculi of +which are equal. + +Atlantic City. H. L. Smith T. S. No. 211. + +Pl. 17, Fig. 17. + + +STAURONEIS EHR. (1843) + +(stauros, a cross, and neis (naus), a boat) + +Frustules free, sometimes geminate; valve as in Navicula but with a +stauros. Cell contents as in Navicula. Mereschkowsky, however, says that +the chromatophores always contain more pyrenoids than are found in +Navicula. Heinzerling gives the number as two to four in each +chromatophore. + +Cleve includes under Naviculae Microstigmaticae all species of Stauroneis, +Pleurostauron, Schizostauron, certain Schizonemae and Naviculae. As a +matter of convenience, and because I have already included certain +Schizonemae and Scoliopleura under Navicula, and because of the small +number of species in our locality, I have arranged them under the three +divisions of Cleve as follows: + +_Stauroneis._--Forms having a true stauros, without diaphragms. + +_Pleurostauron._--Forms like Stauroneis but with diaphragms at the ends. + +_Schizostauron._--Forms having a bifid stauros. + + +STAURONEIS PHOENICENTERON EHR. + +Valve lanceolate, obtuse; striae radiate, 18 in 10 [mu], distinctly +punctate. L. usually 125 [mu] but sometimes 200 [mu]. + +Common in fresh water. + +Pl. 27, Fig. 1. + + +STAURONEIS ANCEPS EHR. + +Valve lanceolate, with rostrate or capitate ends; stauros in some cases +does not reach the margin. The varieties are very numerous. + +_Var. gracilis (Ehr.) Cl._--Valve lanceolate, striae very fine; margin of +stauros striated. L. 100 [mu]. Cape May, N. J. Pl. 27, Fig. 5. + +_Var. amphicephala (Kuetz.) Cl._--Valve capitate at the ends; striae, 24 in +10 [mu]. L. 47 [mu]. Fresh water. Pl. 27, Fig. 7. + +_Var. ?_--Valve with produced ends; striae, 30 or more in 10 [mu]. L. 104 +[mu]. Willistown, Pa. Pl. 27, Fig. 4. + +_Var. ?_--Valve with produced ends; striae, about 28 in 10 [mu], punctate. +L. 47 [mu]. Newtown Square. Pl. 27, Fig. 8. + +_Var. ?_--Valve with produced ends; striae, 22 in 10 [mu], showing a +tendency to form longitudinal rows of puncta as in Stauroneis stodderi +Greenleaf, but the rows are not so evident. L. 60 [mu]. Pavonia, N. J., +artesian well. Pl. 27, Fig. 9. + + +STAURONEIS FRICKEI VAR. ANGUSTA N. VAR. + +Valve lanceolate, gradually tapering to the obtuse ends; terminal fissures +prominent, forking at a distance of 7 [mu] from the ends. Frustules +frequently geminate. L. 173 [mu]. + +Newtown Square. Rare. + +Pl. 26, Fig. 18. + +Near Stauroneis frickei A. S. (Atlas, Pl. 242, Fig. 16), except that the +stauros is narrow at the margin. + + +{89}STAURONEIS SALINA WM. SM. + +Valve lanceolate, obtuse; stauros narrow, with short, scattered striae at +the margin, 18 in 10 [mu], punctate. L. 65 [mu]. + +Along the coast. Common. + +Pl. 27, Fig. 6. + + +STAURONEIS LEGUMEN EHR. + +Valve elliptical-lanceolate, inflated in the middle, with produced +sub-capitate or rostrate ends separated by diaphragms. Stauros wide, +striated at the margins; axial area very narrow; striae radiate, about 26 +(?) in 10 [mu], punctate. L. 28 [mu]. + +Pavonia, N. J., artesian well. + +Pl. 39, Fig. 15. + +In Cleve's description and Van Heurck's figure, the median inflation is +"not larger than the others." In the present form the median inflation is +wider. + + +STAURONEIS ACUTA WM. SM. + +Valve rhombic-lanceolate, obtuse; a diaphragm at each end; stauros widened +outwards; striae, 15 or 16 in 10 [mu], punctate. L. 130 [mu]. + +Blue clay. + +Pl. 27, Fig. 2. + + +STAURONEIS AMERICANA A. S. + +Valve elliptical-lanceolate, obtuse; striae, 14 in 10 [mu]. L. 119 [mu]. + +Pavonia, N. J., artesian well. Rare. + +The only specimen found is asymmetrical with respect to the transverse +axis. + +On Plate 40, Fig. 4, is illustrated an abnormal form of Stauroneis, +apparently near S. acuta, having an elongated central nodule and radiating, +curved and coarsely punctate striae. Blue clay. + + +STAURONEIS SMITHII GRUN. + +Valve lanceolate, inflated in the middle and at the ends, which have +diaphragms and are produced into rostrate apices; stauros reaching the +margin; striae parallel, about 25 in 10 [mu] (28 to 30, Cleve), distinctly +punctate. + +Not uncommon in meadow pools near Newtown Square. + +Pl. 27, Fig. 11. + + +STAURONEIS CRUCICULA (GRUN.) CL. + +Valve lanceolate, with obtuse, produced ends; stauros bifid; striae, 24 in +10 [mu], oblique, parallel to the branches of the stauros, closer at the +ends, punctate. L. 32 [mu]. + +Newtown Square. East Park Reservoir. Rare. + +Pl. 27, Fig. 10. + + +NAVICULA BORY (1826) + +(dim. of navis, a boat) + +Valve linear to elliptical; ends acute, rounded, rostrate, capitate or +truncate; axial area usually distinct; central area distinct, rounded or +rarely extended into a transverse fascia; striae transverse or radiate, +punctate; central area not dilated into a transverse stauros nor into +horns. + +{90}The endochrome in the greater number of species consists of two +chromatophores extending along the zone and sometimes partly over the +valves. Sometimes, however, as in N. hennedyi, N. lyra and N. humerosa, the +bands are on the valves. Certain species have four bands, others eight, and +in one the endochrome is granular. (Mereschkowsky, l. c., p. 9 et seq.) +Pyrenoids are usually absent. On account of the diversity of the +chromatophores, Mereschkowsky considers the genus not homogeneous. The +difficulty of arranging groups according to the cell contents, however, is +so great that, for the present, the species must be described by the usual +characteristics of the valves and divided as follows, according to Cleve, +to the extent of employing the classification of all Naviculoid forms as +applicable, especially to the species of Navicula. Van Heurck's analysis +includes Pinnularia, Trachyneis, Diploneis, Caloneis, Neidium and +Anomoeoneis, which are here separated, while N. lyra and N. hennedyi are +placed in different groups, although they are closely related. In other +respects Cleve's divisions correspond, to some extent, to those of Van +Heurck. + +The genus Navicula at one time included the following: Dictyoneis, +Pleurosigma, Gyrosigma, Caloneis, Neidium, Diploneis, Frustulia, +Trachyneis, Anomoeoneis, Pinnularia and Stauroneis, and few forms with a +raphe escaped. For this reason the diagnosis of the present genus is +somewhat limited. Pleurosigma and Gyrosigma differ from Navicula in their +outline, Dictyoneis in the double stratification, Caloneis in the marginal +lines, Neidium in the median and terminal fissures, Diploneis in the horns, +Frustulia in the terminal nodules, Trachyneis in the stratification of the +valve, Anomoeoneis in the longitudinal arrangement of the puncta, +Pinnularia in the smooth costae and Stauroneis in the stauros. + +As the object of the present work is to aid the student of local forms in +the identification of species by the briefest methods, the further +discussion of the reasons for classification will be left for his +gratification in referring to the authorities on the subject. + + +PUNCTATAE CLEVE + +Valve elliptical to lanceolate; central nodule not stauroid or continued +into lyriform spaces; striae distinctly or coarsely punctate, in radiate +rows. + + +NAVICULA MACULATA (BAIL.) CL. + +Valve lanceolate-elliptical, with produced or sub-rostrate ends; axial area +narrow, wider near the ends and dilated to a rounded, transverse central +area; striae radiate, 6 in 10 [mu], puncta, 7 in 10 [mu], in irregular, +longitudinal rows. L. 90 to 120 [mu] (Cl.). + +_Stauroneis maculata_ Bail. + +_Navicula fischeri_ A. S. + +Blue clay. Along the coast, especially southward. + +Pl. 24, Fig. 1. + + +NAVICULA LATISSIMA GREG. + +Valve oblong-elliptical or elliptical-lanceolate, with sub-cuneate ends; +axial area lanceolate, widened in the middle to an orbicular space; striae +radiate, 7 in 10 [mu], puncta, 11 in 10 [mu], the median striae alternating +with short striae along the sides. L. 50-150 [mu] (Cl). + +Blue clay. Pavonia, N. J., artesian well. + +Pl. 24, Fig. 3. + + +{91}NAVICULA LATISSIMA VAR. ELONGATA (PANT.) CL. + +Valve elliptical-lanceolate, with rounded ends; striae and puncta closer +than in the type form; axial area narrow, widened in the middle; terminal +fissures hook-shaped, turned in different directions. + +_Navicula humerosa_ var. _elongata_ Pant. + +Fossil at Buckshutem, N. J. + +Pl. 24, Fig. 5. + + +NAVICULA FUCHSII PANT. + +Valve elliptical, with slightly produced apices; axial area wide, +lanceolate; central area orbicular; striae alternately longer and shorter +in the middle, 10-12 in 10 [mu]; puncta on the border of the axial area +larger, elongated; median fissures incrassate. + +_Navicula humerosa_ var. _fuchsii_ (Pant.) Cl. + +_Navicula_ (_latissima_ var.?) _fuchsii_ Pant. + +Port Penn, Delaware River. + +Pl. 24, Fig. 6. + + +NAVICULA HUMEROSA BREB. + +Valve lanceolate-elliptical or oblong-elliptical, with sub-cuneate or +sub-rostrate ends; axial area narrow, lanceolate; central area rounded, +somewhat transverse; terminal fissures hook-shaped, in the same direction; +central pores incrassate; striae, 11 in 10 [mu], the middle alternately +longer and shorter, closer at the ends. L. 60-86 [mu]. Variable in size, +outline and fineness of striation. + +N. monilifera Cleve (N. granulata Breb.) differs in having coarser striae. + +Blue clay. Along the coast. + +Pl. 25, Fig. 5. + + +NAVICULA PUSILLA WM. SM. + +Valve ovate-elliptical, with rostrate or sub-rostrate ends; axial area +narrow; central area elliptical; striae radiate, 10-12 in 10 [mu] in the +middle where they are longer and shorter alternately, closer at the ends; +median fissures somewhat incrassate, terminal in the same direction. L. 47 +[mu]. + +Smith's Island, Delaware River. + +Pl. 25, Figs. 4, 6? + +Cleve gives the striae as 13-18 in the typical form, and 11-13 in +varieties. In the form here figured the striation is as stated by De Toni, +but is about 19 at the ends. + +Fig. 6 appears to be a small form of N. pusilla, near lanceolata Grun., at +least according to the figure in "Arctic Diatoms," but not Gregory's +figure. It occurs rarely in fresh water at Newtown Square. It may be a +small form of N. punctulata and, if so, is probably accidental, as the +material is entirely fresh-water. + + +NAVICULA PUSILLA VAR. SUBCAPITATA N. VAR. + +Valve elliptical with rostrate-capitate and truncate ends; striae about 12 +in 10 [mu] in the middle where they are unequal; axial area narrow, +slightly widened in the middle; central pores incrassate, terminal fissures +in the same direction. Differs from type in outline and centre. + +Pavonia, N. J., artesian well. Rare. + +Pl. 25, Fig. 8. + + +{92}NAVICULA DELAWARENSIS GRUN. + +Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, +lanceolate, widened in the middle; striae about 10 in 10 [mu]; in the +middle, much closer at the ends; puncta in the middle, 9 in 10 [mu], closer +and much smaller at the ends. L. 58-95 [mu]. + +Cleve (Le Diatomiste, Vol. 2, p. 14) states that this form is very near N. +pusilla but is much larger. Specimens from Smith's Island measure 58-65 +[mu], from Wildwood, 95 [mu] in length. + +Pl. 25, Fig. 3. + + +NAVICULA PUNCTULATA WM. SM. + +Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, +central area rounded; striae, 11 in 10 [mu], closer at the ends, a few +shorter in the middle; puncta, 10 in 10 [mu]. L. 54 [mu]. + +_Navicula marina_ Ralfs. + +Port Penn, Delaware River (brackish water). + +Pl. 25, Fig. 9. + +"Although this species is described as marine in the Synopsis of Prof. +Smith, I have never found it in purely marine localities" (Donkin). + + +NAVICULA PUNCTATA VAR. ASYMMETRICA LAGERSTEDT + +Valve lanceolate, with rostrate ends; axial area narrow, central area +transverse, irregular; striae radiate, punctate, 12 in 10 [mu]. L. 36 [mu]. + +_Navicula amphibola_ Cleve. + +Blue clay. + +Pl. 27, Fig. 15. + + +NAVICULA BRASILIENSIS VAR. BICUNEATA CL., FORMA CONSTRICTA + +Valve oblong-elliptical, slightly constricted, with cuneate-rostrate ends; +axial area narrow; central area dilated transversely and unilaterally; +striae, 9 in 10 [mu]; puncta closer at the border and in irregular +longitudinal rows in the middle; terminal fissures small, hook-shaped, +turned in the same direction. L. 93 [mu]. + +Corresponds closely to Cleve's variety except in the constriction. + +Blue clay. + +Pl. 25, Fig. 2. + + +NAVICULA LACUSTRIS GREG. + +Valve lanceolate, sub-acute; axial area narrow; central area orbicular; +striae radiate, 14 in 10 [mu], punctate, the median puncta sometimes more +distant than the others. + +Blue clay. Rare. + +Pl. 27, Fig. 12. + + +LYRATAE CL. + +Valve elliptical or elliptical-lanceolate; striae punctate, transverse; +axial area narrow or indistinct; central area expanded on each side into +lyre-shaped or horn-like blank spaces. + + +NAVICULA PRAETEXTA EHR. + +Valve elliptical; lateral areas not regular, with scattered puncta; striae +radiate, 5 or 6 in 10 [mu]; puncta, 7 or 8 in 10 [mu]; along the axial +area, a single or double row of puncta; at {93}the middle of the border, on +each side, two striae approach each other closely with a short stria +between them; terminal fissures small, in the same direction. L. 120 [mu]. + +Port Penn, Delaware River. + +Pl. 24, Fig. 2. + +While variable in size and striation, approaching N. hennedyi, this +species, as here figured, is found in the Miocene and later deposits and is +extant in most parts of the world. + + +NAVICULA IRRORATA GREV. + +Valve oblong-elliptical, with cuneate-rostrate ends; striae, 7 or 8 in 10 +[mu], puncta, 7 in 10 [mu]; axial area bordered by puncta in unequal, +transverse rows. L. 84 [mu]. + +Blue clay. Rare. + +Pl. 24, Fig. 4. + + +NAVICULA HENNEDYI WM. SM. + +Valve elliptical; areas semilanceolate; striae about 11 in 10 [mu], +sometimes longer and shorter on the margin; short rows of transverse striae +along the axial area. + +Blue clay. + +Pl. 25, Fig. 12. + +_Var. circumsecta Grun._--As in the type but with the lateral areas faintly +striate or punctate. + +_Var. manca A. S._--Valve lanceolate-elliptical, the lateral areas narrow +and convergent toward the ends; short rows of transverse striae along the +axial area; striae, 9 in 10 [mu]; central pores incrassate. + +Blue clay. + +Pl. 25, Fig. 11. + + +NAVICULA LYRA EHR. + +Valve elliptical, with rounded, sub-rostrate or sub-cuneate ends; lateral +areas narrow; striae, 6 to 14 in 10 [mu] (Cl.), punctate. L. 50-180 [mu]. + +_Var. ehrenbergii Cl._--Lateral areas constricted in the middle, divergent +at the ends. Cleve refers to Schmidt, Atlas, Pl. 2, Fig. 25, which is not +divergent at the ends. + +Along the coast. + +Pl. 25, Fig. 10. + +A narrower form occurs which has the areas divergent. + +_Var. ?_--Valve elliptical, lateral areas narrow, convergent at the ends +with short rows of punctate striae; marginal striae, 10 in 10 [mu], +punctate. L. 60 [mu]. + +Squan River, N. J. + +Pl. 20, Fig. 5. + +_Var. dilatata A. S._--Valve elliptical, rostrate; lateral areas convergent +in the middle and nearly parallel or convergent at the ends. + +Blue clay. + +Pl. 25, Fig. 13. + +N. lyra is exceedingly variable in outline, fineness of striation and in +the lateral areas. Intermediate forms occur approaching N. hennedyi and N. +spectabilis. In N. hennedyi the lateral areas are broad, semilanceolate, +not narrowed in the middle. In N. spectabilis the lateral areas are broad +and narrowed in the middle. In N. lyra the lateral areas are narrow and +either constricted or not in the middle. In many forms in {94}these three +species the lateral areas are more or less striated or punctate. Cleve does +not consider this a distinction of any importance, although certain +varieties are founded upon it. All three species are very common in the +blue clay and along the coast, but their varieties are too numerous to +describe or figure. + + +NAVICULA SPECTABILIS VAR. EMARGINATA CL. + +Valve elliptical; lateral areas broad, narrowed in the middle, delicately +striated; marginal striae, 10 in 10 [mu]. L. 70 [mu]. + +Blue clay. + +Pl. 25, Fig. 7. + + +NAVICULA PYGMAEA KUETZ. + +Valve elliptical, appearing hyaline; axial and central areas faint; lateral +areas convergent in the middle; striae indistinct, about 25 in 10 [mu]. L. +23 [mu]. + +Brandywine Creek (Palmer). + +Pl. 27, Fig. 23. + + +DECUSSATAE CL. + +Valve elliptical or lanceolate; axial area narrow; central area small; +striae punctate, in transverse and oblique, curved rows. + + +NAVICULA PLACENTA EHR. + +Valve elliptical, with short, rostrate-capitate ends; axial area narrow; +central area elliptical; striae in two directions, the transverse about 22 +(to 27, Cl.) in 10 [mu], the oblique striae crossing in both directions in +curved lines appearing "coarser than the transverse" (Lewis). + +A very peculiar species which, as Cleve remarks, seems not to be allied to +any other. L. about 35 [mu], quite constant in size. It is reported from +Finland, Scotland, Hungary and New Zealand. Dr. Lewis found it in the +Delaware River. It is occasional in the Schuylkill River and the blue clay, +and very abundant on Marchantia and mosses on the wet rocks of the upper +Wissahickon (F. J. Keeley). + +Pl. 27, Fig. 17. + + +LINEOLATAE CL. + +Valve more or less lanceolate; axial area narrow or indistinct; striae +radiate or parallel, lineate, that is, with the puncta closer than the +striae. + + +NAVICULA RADIOSA KUETZ. + +Valve lanceolate with sub-rostrate apices; axial area indistinct; central +area small; striae radiate in the middle, from 6 to 8 in 10 [mu], and +convergent at the ends, about 12 in 10 [mu]. L. 47 [mu]. + +Very common in fresh water. + +Pl. 26, Fig. 17; Pl. 40, Fig. 9. + + +NAVICULA PEREGRINA EHR. + +Valve lanceolate, obtuse; axial area narrow; central area large, rounded or +slightly irregular; striae coarse in the middle, 5 in 10 [mu], radiate; +convergent at the ends, 7 or 8 in 10 [mu]. + +Abundant in brackish water. Delaware River. + +Pl. 26, Fig. 20. + + +{95}NAVICULA CYPRINUS (WM. SM.) + +Valve lanceolate, slightly gibbous in the middle, sub-cuneate at the ends; +axial area narrow; central area small; striae radiate in the middle, 10 in +10 [mu], with shorter, transverse striae intermediate; transverse at the +extreme ends. L. 82 [mu]. + +_Navicula digito-radiata_ var. _cyprinus_ (Ehr. ?) Wm. Sm. Whether the form +here figured is Ehrenberg's or not, it is the species known as Pinnularia +cyprinus Ehr. of Wm. Smith. + +Common in Shark River, N. J. + +Pl. 26, Fig. 21. + + +NAVICULA REINHARDTII GRUN. + +Valve elliptical or elliptical-lanceolate, with broad, rounded ends; axial +area narrow, widened at the ends to the width of the valve; central area +widened transversely to an irregular, quadrate space; striae coarse, 8 in +10 [mu], distinctly lineate, alternately longer and shorter in the middle, +radiate, nearly transverse at the ends. L. 59 [mu]. + +Blue clay. Rare. + +Pl. 26, Fig. 22. + + +NAVICULA LANCEOLATA VAR. ARENARIA (DONK.) CL. + +Valve lanceolate; axial area very narrow or indistinct; central area small, +rounded; striae radiate, 11 in 10 [mu] in the middle, closer at the ends. +L. 47-54 [mu]. + +_Navicula arenaria_ Donk. + +Shark River, N. J. + +Pl. 26, Fig. 23. + + +NAVICULA SALINARUM GRUN. + +Valve elliptical-lanceolate with produced sub-capitate or rostrate ends; +striae radiate in the middle, longer and shorter; transverse at the ends, +lineate. L. 32 [mu]. + +Atlantic City, N. J. + +Pl. 26, Fig. 24. + + +NAVICULA VIRIDULA VAR. ROSTELLATA KUETZ. + +Valve lanceolate with rostrate ends; axial area very narrow, central area +orbicular; striae radiate in the middle, about 12 in 10 [mu], convergent at +the ends and closer. L. 43 [mu]. + +Common in fresh water. + +Pl. 26, Fig. 16. + + +NAVICULA GRACILIS VAR. SCHIZONEMOIDES (EHR.) V. H. + +Valve lanceolate, obtuse; axial area widened in the middle; striae radiate +in the middle, about 12 in 10 [mu], transverse or slightly convergent at +the ends. L. 45-60 [mu]. Occurs in gelatinous tubes; usually found free. + +_Colletonema neglectum_ Thwaites. + +Fresh water. + +Pl. 26, Fig. 19. + + +NAVICULA RAMOSISSIMA (AG.) CL. + +Valve lanceolate, sub-acute; axial area very narrow; central area scarcely +widened; striae, 12 in 10 [mu], parallel throughout. L. 45 [mu]. + +_Micromega ramosissimum_ Ag. + +_Schizonema smithii_ Kuetz. (not Ag.). + +East River, N. Y. + +Pl. 26, Fig. 14. + + +{96}NAVICULA ANGLICA RALFS + +Valve elliptical, with sub-capitate or rostrate ends; axial area narrow, +central area small; striae radiate, 12-13 in 10 [mu], distinctly punctate. +L. 26 [mu]. + +Fresh water. + +Pl. 26, Fig. 26. + + +NAVICULA GASTRUM EHR. + +Valve elliptical, with rostrate ends; axial area narrow, central area +transverse or irregular; striae radiate, 9 in 10 [mu] in the middle. L. 26 +[mu]. + +The form here figured approaches N. anglica. + +Kirkwood Pond, N. J. + +Pl. 26, Fig. 25. + + +NAVICULA DICEPHALA WM. SM. + +Valve linear, with rostrate or rostrate-capitate ends; axial area narrow, +central area rectangular, transverse; striae radiate, 12 in 10 [mu]. L. 32 +[mu]. + +Fresh water. + +Pl. 27, Fig. 16. + + +NAVICULA HUMILIS DONK. + +Valve elliptical, with broad, rostrate ends; axial area narrow; central +area small; striae radiate and distant in the middle, convergent at the +ends, coarse, appearing costate, averaging 9 in 10 [mu]. L. 19 [mu]. As +Donkin states, the striae are "very conspicuous." + +_Navicula hungarica_ var. _capitata_ (Ehr.) Cl. + +_Navicula globiceps_ Lagerstedt, according to Cleve. + +Willistown, Pa. + +Pl. 27, Fig. 24. + + +NAVICULA PINNATA PANT. ? + +Valve lanceolate, obtuse; axial area narrow, widened in the middle; striae +coarse, 7 in 10 [mu] in the middle, radiate, 10 in 10 [mu] at the ends and +transverse, indistinctly lineate. L. 40 [mu]. + +Near _Navicula ardua_ Mann (Diat. Albatross Voy., Cont. U. S. Nat. +Herbarium Vol. 10, Part 5, p. 336, Pl. 53, Fig. 2) which, however, is said +to have "strictly unbeaded costae." + +Pavonia, N. J., artesian well. + +Pl. 27, Fig. 20. + + +NAVICULA PENNATA A. S. + +Valve lanceolate, acute; axial area narrow; central area quadrate, +transverse; striae radiate, coarse, 5 in 10 [mu], lineate. L. 68-95 [mu] +(Cleve). + +Pavonia, N. J., artesian well. + +Pl. 27, Fig. 22. + + +NAVICULA INFLEXA GREG. + +Valve slightly elliptical-lanceolate, sub-acute, smooth at the ends; axial +area narrow, widened in the middle; striae radiate, 11 in 10 [mu], lineate. +Frustule in zone view constricted in the middle. L. 28-45 [mu]. + +Common along the coast. + +Pl. 27, Figs. 18 and 19. + + +{97}NAVICULA OBLONGA KUETZ. + +Valve linear-lanceolate, with broad, rounded ends; margin sometimes +undulate; axial area narrow; central area large, orbicular; striae in the +middle distant, radiate, convergent at the ends and curved or sharply bent, +7 in 10 [mu], lineate. L. 70-200 [mu] (Cleve). + +Blue clay. Occasional in fresh water. + +Pl. 27, Fig. 21. + + +NAVICULA HASTA PANT. + +Valve lanceolate, gently tapering to the obtuse, produced ends; axial area +lanceolate, widened to an orbicular space in the middle; striae radiate, +the median coarse and quite distant, 5 in 10 [mu], becoming closer at the +ends where they are 12 in 10 [mu], lineate. The distance between the median +striae gives the appearance of a stauros. + +Occasional in the blue clay. + +Pl. 27, Fig. 13. + + +NAVICULA HASTA VAR. PUNCTATA N. VAR. + +Valve as in type but with striae in the middle distinctly punctate and +reaching the median line. + +Greenwich Point, Philadelphia. + +Pl. 27, Fig. 14. + + +NAVICULA RHYNCOCEPHALA KUETZ. + +Valve lanceolate, with produced ends; axial area indistinct; central area +small, rounded; striae radiate in the middle, convergent at the ends, 10-11 +in 10 [mu], punctate. L. 42 [mu]. + +Fresh water. Common. + +Pl. 31, Fig. 8. + + +NAVICULA CRYPTOCEPHALA KUETZ. + +Valve lanceolate, with rostrate ends; axial area indistinct; central area +small; striae, 16 in 10 [mu], lineate, radiate in the middle, convergent at +the ends. L. 28 [mu]. + +Common in fresh water. + +Intermediate forms occur between N. rhyncocephala and N. cryptocephala. + +Pl. 31, Fig. 9. + + +NAVICULA LONGA (GREG.) RALFS + +Valve slender, rhombic, elongated, with acute ends; axial area indistinct; +central area small; striae, 6 or 7 in 10 [mu], radiate in the middle, +elsewhere transverse; central pores closely approximate. L. 120 [mu]. + +New Rochelle, N. Y. + +Pl. 31, Fig. 10. + +Cleve refers this form to N. directa var. remota Grun. Some specimens are +found in this locality showing the "generally twisted" median line +mentioned by Gregory. + + +MESOLEIAE CL. + +Valve linear or elliptical; axial area narrow; central area quadrate; +striae radiate, finely punctate. + + +NAVICULA MUTICA KUETZ. + +Valve ovate, elliptical or lanceolate; axial area narrow; central area +dilated into a stauros not reaching the margin; striae about 20 in 10 [mu], +more distant in the middle, radiate, punctate. A punctum occurs on one side +of the central nodule. + +{98}Reported from New Jersey in fresh water. I have not found it. The +figure is from a specimen from another locality. + +Pl. 26, Fig. 6. + + +NAVICULA MINIMA GRUN. + +Valve broadly elliptical, 13-15 [mu] in length; axial area narrow; central +area small but with a quadrate pseudo-stauros which is striated; striae, +about 28 in 10 [mu], radiate. + +Agrees closely with N. saugeri var. Grun. in V. H. Synopsis, Pl. 14, Fig. +16, said to be intermediate between N. minima and N. atomoides Grun. N. +minima var. atomoides Grun. is smaller. + +Common in water-troughs. + +Pl. 26, Fig. 13. + + +NAVICULA PUPULA VAR. BACILLARIOIDES GRUN. + +Valve linear, with rounded ends; axial area linear, expanding on both sides +near the ends of the valve, forming a transverse lunate space; central area +small, apparently expanded into a stauros, which, however, is striated; +striae, 18 in 10 [mu], at the middle, closer at the ends, punctate. L. 54 +[mu]. + +Pavonia, N. J., artesian well. + +Pl. 26, Fig. 9. + + +BACILLARES CL. + +Valve linear or linear-elliptical, with broad ends; axial area narrow, the +median line enclosed in siliceous ribs; striae finely punctate, more +distant in the middle. + + +NAVICULA BACILLUM EHR. + +Valve linear, with rounded ends; axial area enclosed in siliceous ribs and +slightly expanded on each side at the ends; terminal nodules incrassate; +central area small, elliptical; striae, 15 in 10 [mu] in the middle, +transverse, distinctly punctate, closer at the ends L. 47 [mu]. + +Fresh water. + +Pl. 26, Fig. 10. + +Cleve describes the form as having slightly radiate striae in the middle. +There is considerable difference in the descriptions of Cleve, Donkin, +Grunow and Van Heurck, as also in all of the figures. + + +NAVICULA AMERICANA EHR. + +Valve oblong-linear, with rounded ends, sometimes slightly constricted; +axial area about one-half the width of the valve, dilated in the middle; +striae parallel in the middle, radiate at the ends, 15-16 in 10 [mu]. A +punctum is usually found in the central nodule. L. 55-154 [mu]. + +Blue clay. Occasional in fresh water. + +Pl. 26, Fig. 8. + + +DECIPIENTES CL. + +Valve lanceolate, with obtuse ends; axial area narrow; central area +orbicular; striae radiate in the middle and more distant. + + +NAVICULA SEMEN EHR. + +Valve elliptic-lanceolate, with sub-rostrate, truncate apices; axial area +narrow, {99}sinuous; central area orbicular; terminal fissures small, +hook-shaped; striae robust, 7 or 8 in the middle, closer at the ends, +indistinctly punctate or lineolate. + +Blue clay. Not common. + +Pl. 26, Fig. 11. + +Cleve states that this form belongs to the post-glacial deposits and is +found living only in the Hartz Mountains. + + +NAVICULA INTEGRA WM. SM. + +Valve lanceolate with triundulate margins and rostrate-apiculate ends; +striae radiate, more distant in the middle, 20-23 in [mu], punctate; axial +area very narrow, central area rounded or elliptical. L. 33-43 [mu]. + +Pavonia, N. J., artesian well. Common in Chester River, Md. + +Pl. 26, Fig. 5. + + +MICROSTIGMATICAE CL. + +Valve lanceolate; axial area narrow; central area small, rounded; striae +finely punctate, nearly parallel. (Includes here only the division +Libellus.) + + +NAVICULA TUMIDA (BREB.) CL. + +Valve lanceolate, with rounded ends; axial area narrow, central area +elliptical; raphe slightly sigmoid; striae, 13 in 10 [mu], finely punctate, +a few shorter in the middle. + +_Scoliopleura tumida_ (Breb.) V. H. + +Cape May, N. J. + +Pl. 25, Fig. 1. + + +NAVICULA GREVILLEI (AG.) CL. + +Frustules in gelatinous tubes, rectangular; zone with numerous longitudinal +divisions. Valve elliptical-lanceolate, obtuse; axial area narrow, central +area small; striae lineate, about 18 in 10 [mu] in the middle where they +are slightly radiate and more evident, closer near the ends and transverse; +median line with terminal pores distant from the ends. L. 60 [mu]. + +_Schizonema grevillei_ Ag. + +East River, N. Y. + +Pl. 31, Figs. 3 and 4. + + +NAVICULA LIBELLUS GREG. + +Valve rhombic-elliptical, obtuse at the ends; axial area narrow, central +rounded, small; striae punctate, slightly radiate, about 19 in 10 [mu]; +terminal fissures close to the ends, indistinct. L. 60 [mu]. + +Cleve describes this form as having acute ends, while Gregory states that +it is "more obtuse and broader than N. rhombica." Gregory's Figure 101 +apparently shows the ends acute, but he says that the valve view is +"rhombic or elliptic-lanceolate, broad, with obtuse ends" (Diat. of the +Clyde, p. 57, Pl. 6). + +Hackensack Swamp, N. J. + +Pl. 31, Fig. 5. + + +ORTHOSTICHAE CL. + +Valve lanceolate or elongated; axial area narrow; central area sometimes +apparently dilated into a stauros; striae punctate, the puncta in +transverse and longitudinal rows. + + +{100}NAVICULA CUSPIDATA KUETZ. + +Valve rhombic-lanceolate, with acute ends; axial area linear, narrow, not +widened in the middle; striae transverse, 14-19 in 10 [mu] (Cl.). L. 70-150 +[mu]. + +Blue clay. Not uncommon in fresh water. + +Pl. 26, Figs. 1 and 2. + +Fig. 2 represents an inner valve or stratum, with strong costae variable in +size, formerly known as Surirella craticula Ehr. + +_N. cuspidata var. ambigua (Ehr.) Cl._--Valve elliptical-lanceolate, with +rostrate ends, smaller than the type and with finer striae. + +Crum Creek. + +Pl. 26, Fig. 3. + + +NAVICULA SPICULA (HICKIE) CL. + +Valve narrow, lanceolate with acute ends; axial area narrow, central area +dilated into a stauros reaching the margin; transverse striae, 25-29 in 10 +[mu], longitudinal closer. L. 50-130 (Cl.). + +Sometimes confused with N. crucigera. + +_Stauroneis spicula_ Hickie. + +Newark, N. J. + +Pl. 26, Fig. 4. + + +NAVICULA CRUCIGERA (WM. SM.) CL. + +Valve lanceolate, narrow, with acute apices; central nodule a stauros +reaching the margin but crossed by two or three coarser striae; transverse +striae, 12 in 10 [mu], punctate, the puncta about 25 in 10 [mu]. L. 80-100 +[mu] (Cl.). Frustules in gelatinous tubes or free. + +_Schizonema cruciger_ Wm. Sm. + +Pl. 26, Fig. 15. + +Reported as occurring in New York Bay, but I have not seen it. The figure +is from a specimen from another locality. + + +MINUSCULAE CL. + +Valve lanceolate or elliptical, chiefly distinguished by the small size; +axial area indistinct; central area small; striae radiate, very finely +punctate. + + +NAVICULA ATOMUS NAEGELI + +Valve elliptical, 6-8 [mu] in length; striae radiate, 26-30 [mu], closer +near the ends; axial area linear, scarcely widened in the middle. + +Water-troughs and ditches. Probably common, but frequently not noticed +because of its minuteness. A mounting medium of the highest refractive +index, such as realgar, is required to resolve the striae. In the figure +the striae are drawn a little coarser than they appear in most specimens. + +Pl. 26, Fig. 12. + + +LAEVISTRIATAE CL. + +Valve lanceolate, axial area distinct; central area orbicular; striae +coarse, indistinctly punctate, approaching the costae of Pinnularia. + + +{101}NAVICULA YARRENSIS GRUN. + +Valve elliptical-lanceolate, with rounded ends; axial area lanceolate, +widened in the middle; striae, 5 in 10 [mu]. L. 97 [mu]. + +Cape May, N. J. Common. + +Pl. 25, Fig. 14. + +Fig. 15, a smaller form, 65 [mu] in length; striae, 6 in 10 [mu]. + +Fig. 16, 54 [mu] in length; striae, 8 in 10 [mu] (near var. valida Pant.). + + +NAVICULA ELEGANS WM. SM. + +Valve elliptical-lanceolate, with produced ends; axial area very narrow, +central area large, orbicular; striae strongly divergent in the middle, +slightly, if at all, convergent at the ends, curved toward the margin, +indistinctly lineate, 9 in 10 [mu]. L. 95 [mu]. + +Blue clay. Not rare. + +Pl. 31, Fig. 1. + +_Navicula elegans var. cuspidata Cl._--Valve as in type form but smaller +and with rostrate apices; striae, 10 in 10 [mu]. L. 82 [mu]. + +Belmar, N. J. + +Pl. 31, Fig. 2. + +Cleve remarks that the type form is acute and the striae 9, while the var. +cuspidata has 12 striae in 10 [mu]. In Fig. 1, Pl. 31, is represented a +valve having 9 striae in 10 [mu], but not acute, while Fig. 2, with but +slight variation in striae, is more cuspidate. It is probable there are +intermediate variations. + + +NAVICULA PALPEBRALIS BREB. + +Valve elliptical-lanceolate, with acute apiculate ends; axial area broad, +lanceolate; striae radiate, lineate, about 11 in 10 [mu]. L. 60 [mu]. + +Along the coast. + +Pl. 31, Figs. 6 and 7. + +On Plate 40, Fig. 5, is represented an abnormal form of Navicula in which +the central pores are in a line transverse to the longitudinal axis and +each raphe is curved in a line which almost returns to the centre. The +puncta are in curved lines radiating from the rounded hyaline centre. + +Pavonia, N. J., artesian well. + +Weissflog has described valves of Navicula somewhat similar in punctation. + + +PINNULARIA EHR. (1843) + +(pinnula, a small feather) + +Valve linear or nearly so, with rounded ends; axial area broad; central and +terminal areas large; costae smooth, transverse or radiating, usually +convergent at the ends. + +The costae are channels on the inside of the valve, closed, except in the +middle where elliptical foramina, opening into the interior of the valve, +give rise through their terminal margins to the two longitudinal lines on +each side of the valve. The raphe begins as a groove in the side of the +conical central nodule and continues as a cleft at right angles to the +plane of the surface of the valve, in which case the raphe forms a single +line; if the raphe is inclined to the valve surface, then two lines appear +in projection, the upper and lower edges of the cleft. In some forms the +surface of the edge of the raphe on one side is folded or grooved for a +considerable distance, and the opposite edge is elevated into a ridge or +{102}tongue fitting into the groove. In such cases it is possible, in +projection, to see the upper or outer edges of the raphe, the lower edges +and the edges of the tongue and groove, thus showing four lines; sometimes, +when the tongue and groove do not meet, six lines. The so-called inner +channel is the part of the raphe on the inside of the tongue, and the +so-called exterior channel is the part of the raphe on the outside of the +tongue. If, in addition to this formation of the raphe, the plane of +cleavage changes toward the terminal nodules, the lines will cross each +other and, when two are superimposed, disappear altogether. For the careful +examination of the raphe it is necessary to employ large forms, and it is +advisable to use nitrate of silver which remains in the raphe, and, as in +slides mounted by Mr. F. J. Keeley, shows in a beautiful manner the entire +outline of raphe and fissures. The terminal fissures owe their separation +to the different directions taken by the two edges of the raphe on each +side, one edge bending in a wide curve toward the end of the valve, showing +two lines, the upper and lower edges of one side of the raphe when inclined +to the plane of the surface, and the other edge of the raphe turning +suddenly in an opposite direction and ending abruptly in a curve, giving +rise to the appearance, by diffraction, of a punctum. + +Pl. 40, Figs. 13, 14 and 15. + +Endochrome consists of two chromatophores lying on the zones. + +Pinnularia is usually divided into the Majores, or larger, and the Minores, +or smaller forms, the latter being further divided according to their +striae. The following classification is chiefly that of Cleve. + +_Majores._--Valve large, linear with parallel or slightly radiate striae +and broad axial area. + +_Gracillimae._--Valve small, striae parallel or nearly so; axial area very +narrow. + +_Capitatae._--Valve with capitate or rostrate ends; striae radiate. + +_Divergentes._--Striae strongly radiate. + +_Brevistriatae._--Striae short. + +_Distantes._--Striae distant. + +_Tabellariae._--Striae radiate in the middle, strongly convergent at the +ends. + +_Marinae._--Marine forms. + + +MAJORES + +PINNULARIA MAJOR (KUETZ.) WM. SM. + +Valve linear, usually slightly gibbous in the middle and at the ends; raphe +oblique; axial area less than one-third the width of valve, convergent at +the ends; striae, 7 or 8 in 10 [mu], radiate in the middle, convergent at +the ends, crossed by a narrow band. L. ? to 300 [mu]. + +Blue clay. Fresh water. Abundant at Middletown, Delaware Co. (T. C. +Palmer). + +Pl. 28, Fig. 4. + +Fig. 9, Pl. 29, is one of a number of smaller forms which are difficult to +determine, approaching P. viridis. + + +PINNULARIA MAJOR VAR. PULCHELLA N. VAR. + +Valve strongly gibbous in the middle and gradually widened to the rounded +ends; axial area broad, less than one-third the width of the valve, widened +unilaterally in the middle; striae, 7 in 10 [mu], crossed by a band nearly +as wide as the length of the costae and scarcely distinct. L. 273 [mu]. + +{103}The central nodule is scarcely evident, probably because it is not so +thick as in other forms. The outline is near to that of N. mesogongyla and +certain forms of N. nobilis, differing from the latter in the median line, +striae and band which is wider than that of P. latevittata var. domingensis +Cl. + +Hammonton Pond, N. J. + +Pl. 28, Fig. 2. + +A very beautiful form which I cannot find described or figured. It does not +appear to be N. major var. turgidula Cl., which has a narrow band. In the +fossil deposit from Hopkinton, N. H., valves occur similar in outline but +smaller. + + +PINNULARIA NOBILIS EHR. + +Valve slightly gibbous in the middle and at the ends; median line complex; +striae, 4 or 5 in 10 [mu], slightly convergent or parallel at the ends, +crossed by a band one-third as wide as the length of the striae. L. ? to +350 [mu]. + +Blue clay. Fresh water. + +Pl. 28, Fig. 1. + + +PINNULARIA DACTYLUS EHR. + +Valve broad, linear, slightly gibbous in the middle; ends broad, rounded; +median line not complex, sinuous; striae, 4 or 5 in 10 [mu], crossed by a +very broad band. L. ? to 300 [mu]. + +_Navicula gigas_ A. S. + +Blue clay. Fresh water. + +Pl. 28, Fig. 3. + +Forms occur which are with difficulty assigned to either nobilis or +dactylus. + + +PINNULARIA DACTYLUS VAR. DARIANA (A. S.) CL. + +Valve linear-lanceolate, obtuse; axial area broad, less than one-third the +width of the valve; striae, 6 in 10 [mu], crossed by a broad band. L. 220 +[mu]. + +Absecon, N. J. + +Pl. 29, Fig. 3. + + +PINNULARIA DACTYLUS VAR. DEMERARAE CL. + +Valve elliptical-lanceolate, with sub-cuneate ends; axial area lanceolate, +broad in the middle; median line flexuose; striae radiate throughout, 6 in +10 [mu]. L. 150 [mu]. + +Blue clay. + +Pl. 29, Fig. 10. + + +PINNULARIA GENTILIS (DONK.) CL. + +Valve linear, with rounded ends; axial area about one-fourth the diameter +of the valve; striae radiate in the middle, convergent at the ends, 7 in 10 +[mu], crossed by a broad indistinct band. + +Fresh water. Not common. + +Pl. 29, Fig. 1. + + +PINNULARIA TRIGONOCEPHALA CL. + +Valve linear, gibbous in the middle and at the cuneate ends; axial area +wider between the middle and the ends, dilated to an elliptical space in +the middle; striae, 6 in 10 [mu]. L. 145 [mu]. + +Blue clay. + +Pl. 29, Fig. 8. + + +{104}PINNULARIA VIRIDIS NITZSCH + +Valve linear-elliptical, with rounded ends; axial area narrow, widened in +the middle; striae, 6 to 7 in 10 [mu], crossed by a band as wide as +one-third the length of the striae. + +Common in fresh water. + +Pl. 29, Fig. 2. + +Quite variable in size. Approaches P. major by intermediate forms as in +Fig. 9, Pl. 29. + + +PINNULARIA VIRIDIS VAR. FALLAX CL. + +Valve linear, with rounded ends; axial area narrow, slightly widened in the +middle; striae sometimes unilaterally interrupted, nearly parallel, 10 in +10 [mu]. + +Elm, N. J. + +Pl. 29, Fig. 4. + +In Fig. 2, Pl. 30, a form is represented which corresponds closely to +Navicula viridis var. B, of Wm. Smith. It is given as synonymous with var. +fallax; it is bilaterally interrupted. Blue clay. + + +PINNULARIA VIRIDIS VAR. ? + +Valve linear-elliptical, with rounded ends; axial area narrow, widened in +the middle to a transverse fascia which is sometimes unilateral; striae, +14, in the middle, divergent, convergent at the ends and closer, crossed by +a narrow band. L. 45-60 [mu]. Fascia sometimes absent or very narrow. + +Northbrook, Pa. + +Pl. 30, Fig. 17 (represents a form with wider area than usual). + + +PINNULARIA VIRIDIS VAR. CAUDATA N. VAR. + +Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, +widened to an orbicular space in the middle; striae radiate in the middle, +11-12 in 10 [mu], convergent and closer at the ends, crossed by a narrow +band; median line with very long terminal fissures; terminal nodules +noticeable because of the thickening of the edges of the terminal striae. +L. 43 [mu]. + +Fresh water, Newtown Square. Not common. + +Pl. 30, Fig. 18. + + +PINNULARIA SOCIALIS (PALMER) + +Valve linear, with rounded ends; axial area broad, one-third the width of +the valve; striae slightly radiate in the middle, convergent at the ends, +elsewhere parallel, 8 in 10 [mu], crossed by an indistinct band about +one-third the length of the striae. L. 60-120 [mu]. + +This species, discovered by Mr. Palmer near Media, Pa., is remarkable for +the grouping of the frustules "held with girdle sides together by a +siliceous cementing of valve edges and enclosed in a common coleoderm." The +usual number included in a group is four, but sometimes six or eight are +noticed. The frustules adhere near their ends and are so firmly fastened +that boiling in nitric acid and bichromate of potash for fifteen minutes +will not separate them. + +_Navicula socialis_ Palmer (Proc. Acad. Nat. Sci., Phila., 1910, p. 460, +Pl. 35). + +Media, Pa. + +Pl. 29, Fig. 5. + + +{105}PINNULARIA AESTUARII CL. + +Valve linear, with rounded ends; axial area broad, less than one-third the +width of the valve; central area a transverse fascia; striae, 7 in 10 [mu], +parallel except at the ends where they are slightly convergent; median line +flexuose, with short, terminal semicircular fissures. L. 85 [mu]. + +Port Penn, Delaware River. Rare. + +Pl. 29, Fig. 6. + + +GRACILLIMAE + +PINNULARIA MOLARIS (GRUN.) CL. + +Valve very convex, linear, with sub-cuneate ends; axial area narrow, +expanded in the middle to a transverse fascia reaching the margin; striae +divergent in the middle, convergent at the ends, 16 in 10 [mu]. L. 60 [mu]. + +Fresh water. + +Pl. 29, Fig. 15. + + +PINNULARIA LEPTOSOMA GRUN. + +Valve linear, rounded at the ends; axial area narrow; central area a broad +transverse fascia; striae slightly divergent in the middle and convergent +at the ends, 17 in 10 [mu] in the middle, closer at the ends. L. 56 [mu]. + +Fresh water. Not common. + +Pl. 30, Fig. 10. + + +CAPITATAE + +PINNULARIA MESOLEPTA EHR. + +Valve linear, with triundulate margins and capitate ends; axial area +narrow, widened in the middle; striae divergent in the middle, convergent +at the ends, about 12 in 10 [mu]. L. 34 [mu]. + +Common in fresh water. + +Pl. 29, Fig. 13. + + +PINNULARIA MESOLEPTA VAR. STAURONEIFORMIS GRUN. + +Valve triundulate, capitate; axial area narrow, widened in the middle to a +transverse fascia, broader at the margin; striae strongly divergent in the +middle and convergent at the ends, 9-10 in 10 [mu]. L. 70 [mu]. + +Pavonia, N. J., artesian well. Fresh water. + +Pl. 30, Fig. 20. + + +PINNULARIA SUBCAPITATA GREG. + +Valve linear or linear-elliptical, with sub-capitate ends; axial area +distinct, widened to a transverse fascia in the middle; striae divergent in +the middle, convergent at the ends, 13 in 10 [mu]. L. 32 [mu]. + +Fresh water. + +Pl. 29, Fig. 20. + + +{106}PINNULARIA SUBCAPITATA VAR. PAUCISTRIATA GRUN. + +Valve linear-elliptical, with rounded ends; axial area gradually widened +into a broad, transverse fascia; striae divergent in the middle, convergent +at the ends, 11-12 in 10 [mu]. L. 47 [mu]. + +Fresh water. + +Pl. 30, Fig. 16. + + +PINNULARIA TERMES (EHR.) A. S. + +Valve linear, with concave margins and rostrate-capitate ends; axial area +narrow, widened in the middle to an orbicular or sub-quadrate space; striae +divergent in the middle, scarcely, if at all, convergent at the ends, 10 in +10 [mu]. + +Pensauken, N. J., artesian well. + +Pl. 29, Fig. 17. + +This is, I believe, the form figured by Schmidt (Atlas, Pl. 45, Fig. 67). +Cleve refers it to Pinnularia interrupta forma biceps, in which the central +space is rhomboid. + + +PINNULARIA TERMES VAR. STAURONEIFORMIS V. H. + +Valve linear, with concave margins and capitate-rostrate ends; axial area +narrow, widened into a rhomboidal fascia, reaching the margin; striae, 10 +in 10 [mu], divergent in the middle, convergent at the ends. + +_Pinnularia interrupta forma stauroneiformis_ Cl. + +Fresh water. + +Pl. 29, Fig. 14. + + +PINNULARIA APPENDICULATA (AG.) CL. + +Valve linear, with subcapitate ends; axial area narrow; central area a +transverse fascia; striae divergent in the middle, convergent at the ends, +16 in 10 [mu]. L. 43 [mu]. + +Fresh water. Marl pits, Lenola, N. J. (Palmer). + +Pl. 29, Fig. 18. + + +PINNULARIA BRAUNII GRUN. + +Valve linear-lanceolate, with capitate ends; axial area gradually widened +toward the middle and expanded into a fascia reaching the margin; striae +divergent in the middle, convergent at the ends, 11 in 10 [mu]. L. 52 [mu]. + +Pensauken, N. J., artesian well. + +Pl. 29, Fig. 16. + + +PINNULARIA MICROSTAURON (EHR.) CL. + +Valve convex, linear, tapering to sub-cuneate or sub-rostrate ends; axial +area very narrow; central area a broad fascia; striae divergent in the +middle, convergent at the ends, 12 in 10 [mu]. L. 35 [mu]. + +Pavonia, N. J., artesian well. + +Pl. 29, Fig. 19. + +This form does not exactly correspond to Cleve's diagnosis, as the ends are +not broad. All species in the group Capitatae are quite variable. + + +{107}DIVERGENTES + +PINNULARIA DIVERGENS VAR. ELLIPTICA GRUN. + +Valve linear, with rounded ends; axial area widened in the middle to a +transverse fascia; striae, 9 in 10 [mu], divergent in the middle, +convergent at the ends. L. 150 [mu]. + +Fresh water. Not common in this locality. + +Pl. 31, Fig. 13. + + +PINNULARIA CARDINALICULUS CL. + +Valve linear, with rounded ends; axial area wide, less than one-third the +width of the valve, expanded to a transverse fascia; striae divergent in +the middle and slightly convergent at the ends, 9 in 10 [mu]. L. 97 [mu]. + +Blue clay. + +Pl. 30, Fig. 1. + +As a rule, the median fissures in Pinnularia are turned inwards on the side +of the longer edge of the terminal fissures, but not always. In this +specimen the median fissures are turned slightly toward the side of the +shorter edge of the terminal fissures. + + +PINNULARIA LEGUMEN EHR. + +Valve linear, with more or less triundulate margins and broad, capitate +ends; axial area less than one-fourth the width of valve, widened in the +middle; striae strongly divergent in the middle and convergent at the ends, +10 in 10 [mu]. L. 84 [mu]. + +Fresh water. May's Landing, N. J. + +Pl. 30, Fig. 3. + + +PINNULARIA LEGUMEN VAR. ? + +Valve as in type, but with a transverse fascia; striae, 10 in 10 [mu], +curved or bent near the ends. L. 84 [mu]. + +This form is not var. florentina Grun. + +May's Landing, N. J. (with the type). + +Pl. 30, Fig. 4. + + +PINNULARIA BREBISSONII (KUETZ.) CL. + +Valve linear-elliptical, with rounded ends; axial area narrow, widened into +a transverse fascia which is usually broader at the ends; striae divergent +in the middle, convergent at the ends, about 12 in 10 [mu]. L. 40-60 [mu] +(Cl.). + +Fresh water. Common. + +Pl. 29, Fig. 12; Pl. 31, Fig. 11. + +Variable in outline. + + +PINNULARIA MORMONORUM (GRUN.) + +Valve linear, with rounded ends; striae divergent in the middle, convergent +at the ends, 10 in 10 [mu]; axial area rhombic-lanceolate, widened to a +fascia usually reaching the border. L. 62 [mu]. + +_Navicula mormonorum_ Grun. + +Common near Willistown, Pa. + +This form is regarded by Cleve as P. brebissonii, but the axial area +appears to distinguish it. The valves are sometimes narrowed in the middle. + +Pl. 29, Fig. 11. + + +{108}BREVISTRIATAE + +PINNULARIA ACROSPHAERIA (BREB.) CL. + +Valve linear, gibbous in the middle and at the ends; axial area about half +the width of the valve; median line with approximate central pores; median +area punctate; striae nearly parallel, radiate at the ends, 9 in 10 [mu]. +L. 32-180 [mu] (Cl.). + +Blue clay. Recent, fresh water. + +Pl. 30, Fig. 7. + + +PINNULARIA ACROSPHAERIA VAR. TURGIDULA GRUN. ? + +Valve strongly gibbous in the middle; ends rounded; striae, 12-13 in 10 +[mu]. L. 54 [mu]. + +Blue clay, Gloucester, N. J., artesian well. + +Pl. 30, Fig. 8. + + +PINNULARIA BLANDITA N. SP. + +Valve linear, gibbous in the middle, and with rounded ends; striae radiate +in the middle, convergent at the ends, 13 in 10 [mu]; axial area about +one-fourth the width of the valve, widened in the middle; median line with +small semicircular terminal fissures. L. 65 [mu]. + +Pavonia, N. J., artesian well. Rare. + +Pl. 30, Fig. 25. + + +PINNULARIA PARVA (EHR.) CL. VAR. ? + +Valve linear, tapering to the subcapitate ends; axial area broad, +lanceolate; median line with approximate central pores and semicircular +terminal fissures; striae slightly divergent in the middle and convergent +at the ends, 12 in 10 [mu]. L. 58 [mu]. + +Differs from the type in having finer striae. + +Atco, N. J. + +Pl. 30, Fig. 14. + + +PINNULARIA NODOSA FORMA CAPITATA CL. + +Valve triundulate, with capitate ends; axial area about one-fourth the +width of valve; striae parallel, convergent at the ends, 10 in 10 [mu], +sometimes interrupted in the middle. L. 47 [mu]. + +Fresh water. Common. + +Pl. 30, Figs. 15 and 19. + + +PINNULARIA POLYONCA (BREB.) LEWIS + +Valve with triundulate margins, more inflated in the middle, with capitate +ends; axial area very broad; striae marginal, short, 9 in 10 [mu], +divergent in the middle, convergent at the ends. L. 97 [mu]. + +Kirkwood Pond, N. J. + +Pl. 30, Fig. 21. + +The description of Kuetzing (Species Algarum, p. 85), where he states that +the margins are "triundulate, the median inflation larger, apices +rounded-capitate," appears to sufficiently distinguish this species, which +I believe to be the same as Brun's Navicula peripunctata, except that the +form figured (Especes Nouvelles, Pl. 16, Fig. 11) is interrupted in the +middle, a common variation in these forms. Cleve makes Navicula polyonca +Breb. equal Pinnularia mesolepta, but at the same time he considers Lewis' +form and also Brun's as equivalent to Navicula formica Ehr., and calls it +Pinnularia nodosa var. formica Ehr. P. mesolepta has a narrower area than +nodosa. I adhere to Lewis' identification, as in any case it is the form +here figured and is nearly, if not quite, the same as Brun's species. + + +{109}DISTANTES + +PINNULARIA LATA (BREB.) WM. SM. + +Valve linear-elliptical, broad; axial area broad, widened in the middle; +striae slightly radiate in the middle, 3 in 10 [mu]; median line oblique, +the terminal fissures hook-shaped. L. 86 [mu]. + +Blue clay. Not uncommon. + +Pl. 30, Fig. 23. + + +PINNULARIA BOREALIS EHR. + +Valve linear, with rounded or sub-truncate ends; axial area about +one-fourth the width of the valve, widened in the middle; median line with +large hook-shaped terminal fissures; striae, 4 or 5 in 10 [mu]. L. 54 [mu]. + +Blue clay. Occasional in fresh water in a smaller form. Specimens occur +intermediate between P. lata and P. borealis. + +Pl. 30, Fig. 22; Pl. 31, Fig. 12. + + +PINNULARIA BOREALIS VAR. SCALARIS (EHR.) CL. + +Valve narrow, linear; axial area broad, widened into a transverse fascia; +striae, 8 in 10 [mu]. L. 32 [mu]. + +Fresh water. + +Pl. 30, Fig. 24. + + +TABELLARIAE + +PINNULARIA STOMATOPHORA (GRUN.) CL. + +Valve linear, with rounded ends; axial area less than one-third the width +of the valve, gradually widened in the middle to a transverse fascia; on +each side of the central nodule is a lunate space; striae divergent in the +middle, convergent at the ends, 13 in 10 [mu]; terminal fissures very long, +bayonet shaped. L. 75 [mu]. + +Cleve describes a variety continua as not interrupted. In some forms the +fascia is marked by very faint, short striae on the margin. + +Fresh water. Newtown Square. + +Pl. 30, Fig. 12. + + +PINNULARIA GIBBA (KUETZ.) V. H. + +Valve linear, tapering to the subcapitate ends; axial area dilated in the +middle; striae, 10-11 [mu], divergent in the middle, convergent at the +ends. L. 80 [mu]. + +Fresh water. + +Pl. 30, Fig. 5. + + +PINNULARIA MESOGONGYLA (EHR.) CL. + +Valve linear, gibbous in the middle, ends subcapitate; axial area narrow, +widened in the middle to a large orbicular space; striae strongly divergent +in the middle, convergent at the ends, 11 in 10 [mu]. L. 60 [mu]. + +Fresh water. Common. + +Pl. 30, Fig. 6. + + +{110}PINNULARIA STAUROPTERA (GRUN.) CL. + +Valve linear, with slightly triundulate margins tapering to the subcapitate +ends; axial area more than one-third the width of the valve, slightly +widened in the middle; median line with approximate central pores and +semicircular terminal fissures; striae divergent in the middle, convergent +at the ends, 11 in 10 [mu]. L. 82 [mu]. + +May's Landing, N. J. + +Pl. 30, Fig. 13. + +Some of the forms are more triundulate than the specimen figured. + + +PINNULARIA STAUROPTERA VAR. INTERRUPTA CL. + +Valve linear, tapering to the subcapitate ends; axial area broad, widened +in the middle to a transverse fascia; striae divergent in the middle, +convergent at the ends, 10 in 10 [mu]; median pores approximate. L. 118 +[mu]. + +Schuylkill River. + +Pl. 30, Fig. 11. + + +PINNULARIA TABELLARIA (EHR.) CL. + +Valve linear, gibbous in the middle and tapering to the subcapitate ends; +axial area about one-third the width of the valve, widened in the middle; +median line with approximate central pores and bayonet-shaped terminal +fissures; striae sometimes unilaterally interrupted, divergent in the +middle, strongly convergent at the ends, 9 in 10 [mu]. L. 138 [mu]. + +Blue clay. Rare. + +Pl. 30, Fig. 9. + +The form here figured has coarser striae than in the type which is also +usually more capitate. + +P. legumen has triundulate margins, P. mesogongyla has an orbicular space, +while P. gibba has the space widened. According to Cleve, P. gibba has +approximate central pores, as has also P. mesogongyla. In what I have +considered to be P. legumen, the central pores are more approximate than in +the other two species mentioned. In fact, all of the three resemble each +other closely, and are variously named by different authors. The form of P. +gibba here figured, which may be P. stauroptera, is not the typical form of +Wm. Smith, which has a narrow area and central space. There are, however, +among the typical specimens in H. L. Smith's Type Slide No. 275, smaller +valves which show a resemblance. + + +MARINAE + +PINNULARIA RECTANGULATA (GREG.) CL. + +Valve linear, with abruptly rounded ends; axial area very narrow; central +area large, somewhat quadrate; striae, 7-8 in 10 [mu]. L. 78 [mu]. + +_Navicula rectangulata Greg._ + +Shark River, N. J. + +Pl. 29, Fig. 7. + + +{111}EPITHEMIA BREB. (1838) + +(epithema, a cover or lid) + +Frustules epiphytic, solitary, sometimes geminate, adherent on the ventral +side at the ends; in zone view rectangular, sometimes tumid in the middle. +Valve arcuate, having an interior costate stratum or transverse septa +extending to the girdle, often detached, and an exterior valve surface with +transverse rows of puncta. Central and terminal nodules not easily seen; in +some species a true raphe is indicated. + +The resemblance between Epithemia and Eunotia has been already mentioned. +In the shape and striation of the valves there is an approach to Cymbella. + +The genus is divided into two groups, one in which the costae alternate +with double rows of puncta, as in E. turgida, and the other in which the +rows of puncta are more than two. + +The endochrome usually consists of a band lying along the ventral zone and +extending in two flaps on the valves. + + +EPITHEMIA TURGIDA (EHR.) KUETZ. + +Valve arcuate, with ends subcapitate; costae radiate, 4 in 10 [mu], +alternating with double rows of puncta. Median nodule central, the raphe +curved toward the ventral edge which it closely follows. + +Parasitic on algae. Very common in fresh water, especially in ponds. In the +figure the valve is asymmetrical with respect to the transverse axis, an +unusual condition. + +Pl. 31, Fig. 14. + + +EPITHEMIA ARGUS KUETZ. + +Valve with dorsal margin convex, and ventral margin nearly straight; ends +rounded, constricted; costae robust, alternating with more than two rows of +puncta; zone view rectangular, the thickened ends of the costae forming +large nodules in a row along the edge of the valve next to the connecting +zone. + +_Cystopleura argus_ (Ehr.) Kunze. + +Common in fresh water. + +Pl. 31, Figs. 15 and 21. + + +EPITHEMIA ARGUS VAR. ? + +Valve strongly arcuate on the dorsal side and concave on the ventral; +tapering to the rounded but not produced ends; costae at unequal distances, +about 2 in 10 [mu]; granules in transverse rows, 8 in 10 [mu]. L. 100 [mu]. + +Pensauken, N. J., artesian well. + +Pl. 31, Fig. 16. + + +EPITHEMIA MUELLERI A. S. ? + +Valve broad, convex, slightly arcuate, with obtuse, somewhat constricted +apices; costae about 4 in 10 [mu]; striae, 12-14 in 10 [mu]; in zone view +the outline is rectangular, slightly tumid in the middle. L. 78 [mu]. + +Blue clay. + +Pl. 31, Fig. 17. + + +{112}EPITHEMIA ZEBRA VAR. PROBOSCIDEA (KUETZ.) GRUN. + +Valve convex on the dorsal, concave on the ventral side; costae, 3-4 in 10 +[mu], slightly radiating; apices recurved, capitate. + +Blue clay. + +Pl. 31, Fig. 18. + + +EPITHEMIA GIBBERULA VAR. PRODUCTA GRUN. + +Valve narrow, lunate, with produced and arcuate apices; costae radiate, 3-4 +in 10 [mu]; striae, 16-18 in 10 [mu], punctate. L. 58 [mu], usually +smaller. + +Blue clay. + +Pl. 31, Fig. 19. + + +EPITHEMIA MUSCULUS KUETZ. + +Valve short, strongly arcuate on the dorsal, concave on the ventral side; +apices slightly produced; costae radiate, about 5 in 10 [mu]; striae, 15 in +10 [mu], punctate. L. 20-60 [mu]. + +Shark River, N. J. + +Pl. 31, Fig. 20. + + +EPITHEMIA MUSCULUS VAR. CONSTRICTA (BREB.) V. H. + +Frustule elliptical, slightly constricted in the middle. Valve convex on +the dorsal, straight on the ventral side; costae about 4 in 10 [mu]; striae +about 18 in 10 [mu], finely punctate. L. 45 [mu]. + +_Epithemia succinta_ Breb. + +New Rochelle, N. Y. + +Pl. 31, Fig. 22. + + +RHOPALODIA MUELLER (1885) + +(Rhopalodes, like a war club) + +Frustule in zone view linear, linear-elliptical (in our species), or +clavate. Valve reniform or lunate; a raphe, not visible in some species in +the usual position of the valve, is found along the convex edge or keel. +Median and terminal nodules, although very small, can be determined. The +name is more appropriate to the African species which are clavate. Two +species only are found in this locality. + +The chief distinction between Epithemia and Rhopalodia is in the position +of the raphe and the nodules. In R. gibba and R. ventricosa the costae are +parallel and not radiate since the valves are not lunate. + +Chromatophore a single band irregularly divided. + + +RHOPALODIA GIBBA (KUETZ.) MUELLER + +Valve linear, arcuate on the dorsal, straight on the ventral side, reflexed +at the extremities. Costae, 6-7 in 10 [mu]; striae about 14 in 10 [mu]. L. +80-200 [mu]. + +Fresh water. Common. + +Pl. 31, Fig. 23. + +In this species the raphe and nodules can be seen only when the valve is +examined at right angles to its usual position. + + +{113}RHOPALODIA VENTRICOSA (KUETZ.) MUELLER + +Valve gibbous in the middle on the dorsal side, straight on the ventral +side, with reflexed apices; costae, 7 in 10 [mu]; striae, 14-16 in 10 [mu]. +L. 40-100 [mu]. + +The median nodule appears as a minute depression in the middle of the +dorsal side. The two species usually occur together. + +_Epithemia gibba_ var. _ventricosa_ Kuetz. + +Pl. 31, Fig. 24. + + + +SURIRELLOIDEAE + +The Surirelloideae are usually understood to include the genera Surirella, +Podocystis, Cymatopleura and Campylodiscus, all of which resemble each +other more or less, either in having a keel or markings like the divisions +of the keel in Surirella and a median line, or pseudoraphe. The genus +Nitzschia also has a keel, but it does not border each side of the valve as +in Surirella, being found either near one margin or between it and the +centre. Certain of the Surirellae are allied to the group Tryblionella of +the Nitzschiae, while forms of Stenopterobia are distinguished with +difficulty from the group Sigmata. + +The following arrangement, therefore, is intended to include all genera +having a keel or something which resembles it. + +_Hantzschia._--Valve asymmetrical; keels of the two valves opposite each +other. + +_Nitzschia._--Valve asymmetrical; keels not (usually) opposite each other. + +_Surirella._--Valve usually symmetrical; a keel on each border. + +_Cymatopleura._--Valve without an elevated keel, but with markings like +those of Surirella; undulated in zone view. + +_Campylodiscus._--Valves saddle-shaped. + + +HANTZSCHIA GRUN. (1877) + +(named after C. A. Hantzsch) + +Valve arcuate, with rostrate ends; keel puncta short, prolonged into costae +or extending across the valve; median nodule rudimentary; the keels of the +two valves opposite each other. + +Distinguished from Nitzschia chiefly by the position of the keels. +According to Mereschkowsky, however, two species of Nitzschia, N. +lanceolata and N. spectabilis, show the same peculiarity. + +Chromatophores four, two on each of the zones (Mereschkowsky). + + +HANTZSCHIA AMPHIOXYS (EHR.) GRUN. + +Valve slightly arcuate, with rostrate apices; keel puncta, 8 in 10 [mu]; +striae transverse, 16-18 in 10 [mu], punctate. L. 60 [mu]. + +Quite variable. + +Fresh water. + +Pl. 32, Fig. 9. + + +{114}HANTZSCHIA AMPHIOXYS VAR. MAJOR GRUN. + +Valve as in type, but the keel puncta are 5 in 10 [mu] and the striae are +11-12 in 10 [mu]. L. 71 [mu]. + +H. amphioxys var. major Grun. is stated to be 120 [mu] in length. The +present form is smaller but corresponds in puncta and striation. Van Heurck +remarks that it approaches H. virgata. + +Abundant in sand ripples on the beach at Cape May, N. J. + +Pl. 39, Fig. 4. + +Fig. 6, Pl. 39, is drawn from an authentic specimen of Wm. Smith's +Nitzschia amphioxys, from England, and is introduced for comparison. The +central nodule is not evident. + +Fig. 3, Pl. 39, is from a specimen from an unknown locality. The keel +puncta are 6 and the striae 16 in 10 [mu]. + + +HANTZSCHIA VIRGATA (ROPER) GRUN. + +Valve arcuate on the dorsal side, nearly straight on the ventral side, with +rostrate, recurved apices; keel puncta prolonged to one-third the width of +the valve, 4 in 10 [mu]; transverse striae, 9-10 in 10 [mu]. L. 115 [mu]. + +Shark River, N. J. (Kain). + +I have not been able to find this form on our coast. The figure is drawn +from a specimen from another locality. + +Pl. 32, Fig. 23. + + +HANTZSCHIA MARINA (DONK.) GRUN. + +Valve with dorsal margin slightly arcuate, ventral margin straight; apices +rostrate and recurved; keel puncta, 6 in 10 [mu], prolonged into costae +across the entire valve; transverse striae, 12 in 10 [mu], in double rows +of alternating puncta between the costae. L. 106 [mu]. + +_Epithemia marina_ Donkin. + +Along the coast. + +Pl. 32, Fig. 22. + + +NITZSCHIA HASSALL (1845), em. GRUN. (1880) + +(named after Christian L. Nitzsch, of Halle) + +Frustules usually free, sometimes enclosed in tubes or united into a +filament. Valves keeled, the keels of the two valves usually diagonally +opposite (see Hantzschia); keel puncta short or prolonged. + +According to Mereschkowsky, there are at least two endochrome plates placed +transversely on the zones; sometimes there are from four to six plates, in +one species twenty granules and in another no trace of any endochrome +whatever. + +The following analysis is that of Grunow as given in Cleve and Grunow's +"Arctic Diatoms," and adopted and illustrated by Van Heurck in his +"Synopsis." + + +GROUPS + +1. _Tryblionella._--Keel very excentric, valve often folded; keel puncta +indistinct, usually the same in number as the striae. + +2. _Panduriformes._--Valve broad, constricted in the middle, with more or +less evident fold; keel very near the edge; keel puncta quite evident or +apparently wanting. + +{115}3. _Apiculatae._--Keel very near the edge; valve linear or somewhat +narrower in the middle; striae on the longitudinal fold fainter than on the +remaining surface, or wanting; puncta not in quincunx. + +4. _Pseudo-Tryblionella._--Keel more or less close to the edge; valve with +a more or less deep longitudinal fold over which the striae are spread in +the same way as over the remaining surface; keel puncta always distinct. + +5. _Circumsutae._--Valve with more or less wide longitudinal fold; keel +very excentric; keel puncta quite evident; surface of valve irregularly +punctate and also traversed by rows of delicate puncta which belong to a +different layer of the valve. + +6. _Dubiae._--Like the group Pseudo-Tryblionella, but the valves are not so +much folded; frustules sometimes narrowed in the middle. The separation of +species is difficult and, in part, doubtful. Keel excentric. + +7. _Bilobatae._--Like the group Dubiae, but with more central keel and so +forming a transition to the group Pseudo-Amphiprora; valves without +longitudinal folds. + +8. _Pseudo-Amphiprora._--Valve with quite central, sharp keel, arcuate, +without longitudinal fold; keel puncta always evident; frustule narrowed in +the middle with more or less marked central nodule. + +Includes two species not found in this locality. + +9. _Perrya._--Valve arched with very sharp central keel; not narrowed in +the middle; keel puncta mostly on short or long lines which are sometimes +interrupted. + +Includes six species not found in this locality. + +10. _Epithemioideae._--Keel excentric; keel puncta extended into costae +across the entire valve. + +11. _Grunowia._--As in the group Epithemioideae, except that the costae are +shorter, not extending across the valve; keel very excentric. + +12. _Scalares._--Like Grunowia, but with sharper, somewhat excentric keel; +transverse section of frustule quadrangular. + +13. _Insignes._--Like Scalares, but with more central keel so that many of +the forms are near the group Perrya; frustule somewhat sigmoid. + +14. _Bacillaria._--Keel central or nearly so; valve somewhat arched; keel +sharp, as in the group Insignes. + +15. _Vivaces._--Keel moderately excentric; valve, according to position, +semi-lanceolate, with keel puncta in short rows, or lanceolate with quite +central keel. The valves have in many positions a resemblance to +Hantzschia, so that N. vivax frequently becomes confounded with a form of +H. amphioxys. The median keel puncta are not distant and a central nodule +is not evident as is the case in all species of Hantzschia. + +16. _Spathulatae._--Like the group Bacillaria, but usually with very +delicate striated valves; keel in valve view usually bordered with two +parallel lines. + +17. _Dissipatae._--Like Vivaces and Spathulatae, but with smaller central +keel and without parallel lines. Valves usually small, very delicately +striated; no central nodule. + +18. _Sigmoideae._--Keel quite central; no parallel lines; frustule sigmoid; +valve without longitudinal furrow; keel puncta not extended; no central +nodule evident. + +19. _Sigmata._--Like Sigmoideae, but with a more excentric keel. + +20. _Obtusae._--Like Sigmata, with a more or less excentric keel which has +in the middle a small bending to the inside; middle keel puncta somewhat +more distant than the others, and between them a central nodule evident. + +{116}21. _Spectabiles._--Valve large, slightly arcuate, with excentric +keel; no longitudinal folds; keel puncta somewhat extended over the valve +but much less than in the group Insignes, and often scarcely perceptible. + +22. _Lineares._--Keel somewhat excentric, but less than in Spectabiles; +frustule straight, sometimes a little constricted in the middle, so that a +transition is shown to the groups Dubiae and Bilobatae. Valve without +longitudinal fold; keel puncta round or somewhat angular, scarcely +extended. + +23. _Lanceolatae._--Valve lanceolate, linear-lanceolate or rarely +elliptical, with very excentric keel; not folded; keel puncta not extended. + +24. _Nitzschiella._--Valve with excentric keel and long, produced apices. + + +TRYBLIONELLA + +NITZSCHIA TRYBLIONELLA HANTZSCH + +Valve elliptical-lanceolate, with subacute apices; longitudinal fold well +marked; striae coarse, transverse, 5 in 10 [mu]; indistinct puncta +intermediate between the striae. L. 45 [mu]. Quite variable. + +Blue clay. + +Pl. 32, Fig. 8. + + +NITZSCHIA GRANULATA GRUN. + +Valve elliptical or elliptical-lanceolate; striae in double rows, each row +of three or four small puncta along the margin and rows of large puncta +about 6 in 10 [mu] across the valve. L. 28-44 [mu]. + +Blue clay. Along the coast. + +Pl. 32, Fig. 3. + + +NITZSCHIA NAVICULARIS (BREB.) GRUN. + +Valve elliptical-lanceolate, with acute apices; striae on one side a double +row of large and small puncta, and on the other side radiate short rows of +large puncta, 7 in 10 [mu]; middle of valve hyaline. L. 35-60 [mu]. + +Blue clay. Not common. + +Pl. 32, Fig. 4. + + +NITZSCHIA COMPRESSA (BAIL.) + +Valve elliptical-lanceolate, sometimes acuminate; striae, 6 or 7 in 10 +[mu], coarsely punctate. L. 56 [mu]. + +_Pyxidicula compressa_ Bailey. + +_Nitzschia punctata_ (Wm. Sm.) Grun. + +_Tryblionella punctata_ Wm. Sm. + +Common along the coast. + +Pl. 39, Fig. 7. + +Var. minor (H. L. Smith).--Valve acuminate; striae, 8 in 10 [mu]. L. 22 +[mu]. + +_Pyxidicula compressa_ var. _minor_ H. L. Smith, Type Slide No. 431. + +Pl. 39, Fig. 8. + +The smaller forms occur northward, while the larger are found southward. +This is unquestionably Bailey's form, as indicated by his figure and by the +fact that it is found everywhere along the coast. Wm. Smith's T. punctata +is the same species, although the puncta are smaller. + + +{117}PANDURIFORMES + +NITZSCHIA PANDURIFORMIS GREG. + +Valve elliptical, constricted in the middle, with sub-cuneate apices; +longitudinal fold, with a punctate longitudinal line; striae transverse and +oblique, 15 in 10 [mu]; keel puncta, 6 in 10 [mu]. L. 108 [mu]. + +Along the coast. More often found southward. + +Pl. 39, Fig. 2. + + +NITZSCHIA PANDURIFORMIS VAR. MINOR GRUN. + +Valve elliptical, constricted in the middle, with cuneate apices; keel +puncta, 9 in 10 [mu]; striae in transverse and oblique lines about 20 in 10 +[mu]; longitudinal fold bordered by a punctate line. L. 34 [mu]. + +Pavonia, N. J., artesian well. + +Pl. 32, Fig. 5. + +The var. continua Grun. is reported as occurring in Shark River. It varies +in having the longitudinal fold punctate. It is also usually smaller than +var. minor. + + +APICULATAE + +NITZSCHIA APICULATA (GREG.) GRUN. + +Valve oblong-linear, with cuneate-apiculate apices; striae punctate, +apparently interrupted or pervious, about 18 in 10 [mu]. L. 26 [mu]. + +Chester River, Md. + +Pl. 32, Fig. 6. + +The puncta are continued across the valve, but are less distinct on the +fold. The figure shows the entire frustule with the fold on each valve. The +valves are sometimes slightly constricted. + + +NITZSCHIA ACUMINATA (WM. SM.) GRUN. + +Valve linear, sometimes slightly constricted in the middle, with acuminate +apices; longitudinal fold entirely without or with indistinct striae; keel +puncta not evident; striae, 14-15 in 10 [mu]. L. 82 [mu]. + +Port Penn, Delaware River. + +Pl. 32, Fig. 13. + + +NITZSCHIA PLANA WM. SM. + +Valve linear; apices acute, slightly constricted in the middle; +longitudinal fold further from the keel than the margin, broad, with +scattered puncta; striae subtle, irregular, interrupted, about 18 in 10 +[mu]; keel puncta oblong, 3-6 in 10 [mu]. L. 100-170 [mu]. + +Blue clay. Along the coast. + +Pl. 32, Fig. 2. + + +{118}PSEUDO-TRYBLIONELLA + +NITZSCHIA LITORALIS VAR. DELAWARENSIS GRUN. + +Valve linear, with obtusely rounded cuneate ends, scarcely, if at all, +constricted in the middle; longitudinal fold wide; keel puncta, 5 or 6 in +10 [mu], sometimes confluent; striae obscure, about 21 in 10 [mu]. L. 75 +[mu]. + +Delaware River. + +Pl. 32, Fig. 12. + +This form is drawn from a slide of Christian Febiger containing an +abundance of specimens from Delaware City, and marked "Nitzschia dubia." + + +CIRCUMSUTAE + +NITZSCHIA CIRCUMSUTA (BAIL.) GRUN. + +Valve elliptical, sometimes more than 200 [mu] in length; longitudinal fold +more or less conspicuous; keel puncta about 4 in 10 [mu], the middle +distant with the appearance of a nodule; striae irregular, subtle, finely +punctate, frequently interrupted. + +_Surirella circumsuta_ Bail. + +_Tryblionella scutellum_ Wm. Sm. + +Common in brackish water. + +Pl. 32, Fig. 1. + + +DUBIAE + +NITZSCHIA DUBIA WM. SM. + +Valve linear, scarcely, if at all, constricted in the middle, with cuneate, +produced, apiculate apices, somewhat recurved; keel very excentric; puncta +sometimes partly prolonged, about 9 in 10 [mu]; striae, 20-24 in 10 [mu]. +L. 93 [mu]. + +Reported from along the New Jersey coast. I have not seen it. It is +generally regarded as fresh-water. Slides sometimes labelled N. dubia are +in reality N. litoralis var. delawarensis. + +Pl. 39, Fig. 5. + +The figure is drawn from a specimen from another locality. + + +BILOBATAE + +NITZSCHIA BILOBATA WM. SM. + +Valve linear-lanceolate, constricted in the middle, apiculate at the ends; +keel puncta 6 in 10 [mu], prolonged unequally across part of the valve, the +two median sub-remote; striae, 16 in 10 [mu]. Frustule oblong, truncate, +constricted in the middle. L. 120 [mu]. + +Shark River, N. J., Chester River, Md. + +Pl. 32, Figs. 10 and 11. + + +EPITHEMIOIDEAE + +NITZSCHIA EPITHEMIOIDES GRUN. + +Valve linear, with cuneate, rostrate apices; slightly constricted on the +keel side; keel puncta, 8 or 9 in 10 [mu], extending as costae across the +valve; striae delicate, 22 in 10 [mu]. L. 47 [mu]. + +Brackish water, Long Island Sound. + +Pl. 32, Fig. 21. + + +{119}GRUNOWIA + +NITZSCHIA TABELLARIA GRUN. + +Valve rhomboidal, inflated in the middle; apices produced; keel puncta +extend in costae across half of the valve, 7 in 10 [mu]; striae transverse, +about 22 in 10 [mu]. L. 20 [mu]. + +_Dimerogramma sinuatum_ Thwaites. + +_Nitzschia sinuata_ var. _tabellaria_ (Grun.) V. H. + +Schuylkill River. Not common. + +Pl. 32, Fig. 7. + + +SCALARES + +NITZSCHIA SCALARIS (EHR.) WM. SM. + +Valve linear, with obtusely conical apices; costae transverse, extending +more or less to one-third the width of the valve, 3 or 4 in 10 [mu]; +striae, 9 or 10 in 10 [mu], punctate. Length of valve quite variable, up to +480 [mu] (Cleve). + +A well-known form, abundant in salt marshes and more or less brackish +water. + +Pl. 33, Fig. 6. (To the right of the figure is an outline of the valve +reduced one-third.) + + +INSIGNES + +NITZSCHIA INSIGNIS GREG. + +Valve nearly linear or linear-lanceolate; apices broad, slightly produced, +obtuse; keel puncta extended into short costae, 4 or 5 in 10 [mu]; striae +about 14 in 10 [mu]. Length variable up to 400 [mu]. + +Delaware Bay. + +Pl. 33, Fig. 8. + + +BACILLARIA + +NITZSCHIA PAXILLIFER (O. F. MUELLER) HEIBERG + +Frustules united in a filament, afterwards free; valve lanceolate with +nearly central keel; keel puncta, 7-9 in 10 [mu]; striae about 21 in 10 +[mu]. L. 110 [mu]. + +_Vibrio paxillifer_ O. F. Mueller. + +_Bacillaria paradoxa_ Gmelin. + +_Nitzschia paradoxa_ (Gmelin) Grun. + +Brackish water or streams subject to its influence. + +Pl. 33, Figs. 13 and 14. + +Otto Frederick Mueller, in 1786, published at Copenhagen a work on +"Infusorial Animalcules," including a description of a Vibrio which he +named paxillifer, obviously alluding to the partially-extended frustules +bearing at the end a tablet-like bundle. Two years later, Gmelin described +the same form as Bacillaria paradoxa, a name still used. Heiberg, however, +in 1863, placed the form under Nitzschia where it properly belongs and +called it Nitzschia paxillifer (O. F. Mueller). I have adopted Heiberg's +name. + +Perhaps the most remarkable of all diatoms. Many species possess the power +of motion, which, however, is evident only in the free frustule. In N. +paxillifer, the movement of the frustules occurs without the loss of +continuity or adherence to each other, so that, while at one time the +adnate frustules form a narrow filament, like that of Fragilaria, at +another {120}time they move laterally to their extreme length and form a +thread of frustules adherent at their ends, later resuming their original +position. The motion is repeated at intervals of from five to ten seconds. +No satisfactory explanation of the movement has ever been made. In the +filamentous form the frustules adhere to water-plants. + + +VIVACES + +NITZSCHIA FLUMINENSIS GRUN. + +Valve lanceolate, apices produced; keel puncta, 4-6 in 10 [mu], partly +extended in short costae; striae transverse, 14-15 in 10 [mu], punctate; +keel without a pseudo-nodule. L. 73 [mu]. + +Common at Greenwich Point, Philadelphia. + +Pl. 32, Fig. 16. + +The form here figured is smaller than the type, which is from 130-160 [mu] +in length. + + +SPATHULATAE + +NITZSCHIA SPATHULATA BREB. + +Frustule linear, truncate, dilated at the ends; zone with longitudinal +folds; valve lanceolate, keel central; apices acute, with an elevated +appendage; keel puncta, 5-6 in 10 [mu]; striae very fine. L. 56 [mu]. + +Atlantic City and Cape May, N. J. (Lewis). + +Pl. 40, Fig. 3. + + +DISSIPATAE + +NITZSCHIA DISSIPATA (KUETZ.) GRUN. + +Valve lanceolate, with sub-rostrate apices; keel excentric; keel puncta +about 6 in 10 [mu]; striae, 14 in 10 [mu]. L. 20-40 [mu]. + +Fresh and brackish water. + +Pl. 40, Fig. 7. + + +SIGMOIDEAE + +NITZSCHIA MACILENTA GREG. + +Frustule sigmoid, truncate at the ends; valve linear, with sub-acute apices +and nearly central keel; keel with 5-6 puncta in 10 [mu]; striae obscure, +about 25 to 28 (?) in 10 [mu]. Length variable, up to 490 [mu]. + +As the valve is usually seen when the keel is on the margin, the outline +(reduced one-third, shown to the left of the figure) is, as a rule, +sigmoid. + +Delaware Bay. + +Pl. 33, Fig. 7. + + +NITZSCHIA VERMICULARIS (KUETZ.) HANTZSCH + +Valve linear, sigmoid, attenuated toward the obtuse ends; keel puncta, 9 in +10 [mu], quite distinct; striae very fine. L. 105 [mu]. + +Fresh-water pools. + +Pl. 32, Fig. 24; Pl. 33, Fig. 9. + + +{121}SIGMATA + +NITZSCHIA SIGMA (KUETZ.) WM. SM. + +Frustule linear, sigmoid; valve linear, slightly sigmoid, tapering to the +sub-acute apices; keel excentric, puncta, 8 in 10 [mu]; striae, 20-24 in 10 +[mu]. L. to 250 [mu]. + +Along the coast. + +Pl. 39, Fig. 13. + + +NITZSCHIA SIGMATELLA GREG. + +Valve linear, sigmoid, slightly attenuated toward the obtuse apices; keel +excentric, puncta, 8-10 (?) in 10 [mu]; striae delicate, 25-30 in 10 [mu]. +L. to 400 [mu]. The keel puncta are quite obscure. + +_Nitzschia curvula_ Wm. Sm. + +_Nitzschia sigma_ var. _curvula_ (Wm. Sm.) De Toni. + +Fresh water. Hammonton Pond; May's Landing, N. J. + +Pl. 33, Figs. 4 and 5. + +Gregory remarks that the keel puncta are seen in some specimens. In both of +the forms figured I have counted 30 striae in 10 [mu], but, after many +examinations, I have not been quite certain about the keel puncta. The +general appearance of the valves in any position is that of a Stenopterobia +or Surirella anceps, with which it occurs. + + +NITZSCHIA CLAUSII HANTZSCH + +Valve linear, slightly sigmoid, tapering to the sub-capitate ends; keel +puncta, 11 in 10 [mu]; striae subtle. L. 40 [mu]. + +Abundant in Ridley Creek, Delaware Co. (Palmer). + +Pl. 32, Fig. 20. + + +OBTUSAE + +NITZSCHIA OBTUSA WM. SM. + +Frustule sigmoid, rounded at the ends; keel somewhat excentric, inflexed in +the middle, the two median puncta distant; keel puncta, 5-6 in 10 [mu]; +striae, 26 in 10 [mu]. L. to 300 [mu]. + +Along the coast. + +Pl. 39, Fig. 16. + + +NITZSCHIA OBTUSA VAR. FLEXELLA H. L. SMITH + +Valve more attenuate at the ends than the type and smaller. + +Pl. 39, Fig. 14. + + +NITZSCHIA OBTUSA VAR. SCALPELLIFORMIS GRUN. + +Valve linear, with apices unilaterally truncate; keel excentric; keel +puncta, 8 in 10 [mu]; striae, 26 in 10 [mu]. L. 48 [mu]. + +Along the coast. + +Pl. 32, Fig. 17. + + +{122}SPECTABILES + +NITZSCHIA SPECTABILIS VAR. AMERICANA GRUN. + +Frustule linear, slightly constricted in the middle, with sub-cuneate ends; +valve linear, slightly arcuate, tapering to the sub-rostrate ends; keel +excentric, keel puncta sometimes confluent, 4-6 in 10 [mu], prolonged into +short costae; striae distinct, 14 in the middle, 18 at the ends in 10 [mu] +(but variable in different specimens). L. 186 [mu]. + +Blue clay, especially at Tioga St. + +Pl. 33, Fig. 3; Pl. 39, Fig. 1. + +This is, probably, one of the most beautiful of the Nitzschiae. It +sometimes, according to De Toni, reaches a length of 520 [mu]. + +Grunow states that his variety is found in the S. Bridgeton deposit. In a +slide of Moeller labelled "Bridgeton, Maine," I find specimens identical in +every respect with the Philadelphia form. + + +LINEARES + +NITZSCHIA LINEARIS (AG.) WM. SM. + +Valve linear, slightly inflexed in the middle; keel excentric; keel puncta, +8-9 in 10 [mu], the two median distant; striae about 30 in 10 [mu]. +Frustules in zone view narrowed toward the ends, truncate. L. 75 [mu]. + +Very common in fresh water. + +Pl. 32, Fig. 18. Fig. 20, Pl. 40, a transverse section of frustule. + + +LANCEOLATAE + +NITZSCHIA PALEA (KUETZ.) WM. SM. + +Valve linear-lanceolate, slightly rostrate at the apices; keel puncta, 10 +in 10 [mu], the median not distant; striae, 33-36 in 10 [mu]; zone view +linear, with rounded ends. L. 25-65 [mu]. + +Fresh water. + +Pl. 32, Fig. 15. + + +NITZSCHIA AMPHIBIA GRUN. + +Valve lanceolate, apices sometimes slightly produced, rounded; keel puncta, +8-9 in 10 [mu]; striae, 16 in 10 [mu]. L. 20-32 [mu]. + +Fresh water. + +Pl. 32, Figs. 14 and 25. + + +NITZSCHIA COMMUNIS RAB. + +Frustule linear, slightly attenuated at the obtuse ends; valve +elliptical-lanceolate, attenuated toward the obtuse ends; keel puncta, 12 +in 10 [mu]; striae more than 30 in 10 [mu]. L. 35 [mu]. + +Fresh water. + +Pl. 32, Fig. 19. + + +NITZSCHIA INTERMEDIA HANTZSCH + +Valve linear-lanceolate; keel puncta, 8 in 10 [mu]; striae about 24 in 10 +[mu]. L. 100 [mu]. + +Crum Creek. Not common. + +Pl. 33, Fig. 2. + + +{123}NITZSCHIELLA + +NITZSCHIA LONGISSIMA (BREB.) RALFS + +Valve linear-lanceolate, with exceedingly long horns or beaks; keel puncta +about 10 in 10 [mu]; striae about 16 in 10 [mu]. L. to 500 [mu]. + +Shark River, N. J. + +Pl. 33, Fig. 1. + +Forma parva V. H.--Keel puncta, 10-12 in 10 [mu]. L. 70 [mu]. + +East Park Reservoir, Philadelphia. + +Pl. 33, Fig. 10. + +Differs from N. closterium (Ehr.) Wm. Sm. in the keel puncta. + +The type form occurs in brackish and salt water. The occurrence of the +variety in fresh water is another instance of the finding of presumably +brackish forms in the water supply of the city. If these cases prove to be +unusual, it may be because of one of two reasons. The Schuylkill River, +before the building of the dam at Fairmount, was tidal as far as the Falls +of Schuylkill, and brackish influences, while not now existent, may have +caused the growth of forms which now survive. Another reason may be that +the opening of the locks at Fairmount Dam may cause a slight admission of +brackish forms from tidal water below. The abundance of the brackish +species appears to indicate that the first reason is the more plausible. + + +NITZSCHIA REVERSA WM. SM. + +Valve lanceolate extended into beaks or horns curving in opposite +directions; keel puncta not evident; striae, "20-26" in 10 [mu]. L. 70 +[mu]. + +Brackish water. Abundant in Duck Creek, Delaware River. + +Pl. 33, Fig. 11. + + +NITZSCHIA ACICULARIS (KUETZ.) WM. SM. + +Valve lanceolate, with beaks or horns about half the length of the median +part of the valve; keel puncta, 18 in 10 [mu]; striae exceedingly delicate, +"about 40 in 10 [mu]." L. 45 [mu]. + +Fresh water. Darby Creek. + +Pl. 33, Fig. 12. + + +HOMOEOCLADIA AG. (1827) + +(homoios, like, and clados, a branch) + +Frustules like Nitzschia, but enclosed in branching or simple tubes. + + +HOMOEOCLADIA FILIFORMIS WM. SM. + +Frustule linear, tumid in the middle, obtuse at the ends; valve +linear-lanceolate, with somewhat acute apices; keel central or nearly so; +keel puncta, 8 in 10 [mu]; striae delicate. L. 108 [mu]. + +Fresh and brackish water. Newark, N. J. + +Pl. 33, Fig. 15. + + +{124}SURIRELLA TURPIN (1828) + +(named after Dr. Suriray, a physician of Havre) + +Valve linear, elliptical or ovate; pseudoraphe linear or lanceolate; a +marginal keel forming wings or alae seen in zone view; costae short or +reaching the pseudoraphe, frequently with intercostal striae more or less +evident. + +The genus is divided by Grunow according to the length and form of the +costae. I include Stenopterobia. + +Section 1.--Costae of nearly equal width throughout, reaching the +pseudoraphe. + +Section 2.--Costae short or marginal. + +Section 3.--Costae dilated at the margin, attenuated toward the +pseudoraphe. + +Section 4.--Valve having the appearance of Nitzschia, with inconspicuous +alae (Stenopterobia). + +The endochrome consists of two laminate chromatophores, one on each valve. + +The auxospores are single, originating from the union of two frustules (H. +L. Smith). + + +SECTION 1 + +SURIRELLA BISERIATA (EHR.) BREB. + +Valve lanceolate, subacute at the ends; costae robust, about 2 in 10 [mu], +parallel in the middle, radiate at the ends; pseudoraphe narrow. L. 100 +[mu]. + +_Surirella bifrons_ Ehr. + +Fresh water. + +Pl. 39, Fig. 12; Pl. 35, Fig. 2 (smaller form). + + +SURIRELLA LINEARIS WM. SM. + +Valve linear, with cuneate ends, slightly constricted in the middle; costae +parallel, 2-3 in 10 [mu]. L. 90 [mu]. + +Fresh water. + +Pl. 35, Fig. 8. + + +SURIRELLA AMPHIOXYS WM. SM. + +Valve oblong-linear, with cuneate ends; pseudoraphe narrow; costae, 3-4 in +10 [mu]; striae, 14-16 in 10 [mu], somewhat radiate. L. 34-54 [mu]. + +_Surirella moelleriana_ Grun. + +Fresh and brackish water. Common along the coast. + +Pl. 35, Figs. 12 and 13. + + +SURIRELLA ROBUSTA EHR. + +Valve linear-ovate; pseudoraphe wide; alae prominent; costae wide, 1-1/4 in +10 [mu]. Frustule in zone view clavate. L. 200-365 [mu]. + +Fresh water. + +Pl. 36, Fig. 2. + + +{125}SURIRELLA SPLENDIDA (EHR.) KUETZ. + +Valve ovate; costae, 1-1/2 to 2 in 10 [mu]; pseudoraphe linear, narrow. L. +125-200 [mu]. + +Fresh water. + +Pl. 35, Fig. 3. + +S. splendida is smaller than S. robusta and wider in proportion, but, as +intermediate forms occur, it is difficult to distinguish between them. + + +SURIRELLA ELEGANS EHR. + +Valve ovate, rounded at one end and acute at the other; pseudoraphe +lanceolate, narrow; costae, 1-1/2 in 10 [mu]; striae subtle, 22 in 10 [mu]. +Frustule in zone view cuneate. L. 180-220 [mu]. + +Fresh water. + +Pl. 36, Fig. 1. + + +SURIRELLA STRIATULA TURPIN + +Valve broad, obovate or elliptical, rounded at each end; costae, 1-1/4 in +10 [mu], curved at the ends; striae, 14 in 10 [mu]. Frustule in zone view +cuneate; marginal alae quite robust. L. 100-160 [mu]. + +Blue clay. Brackish water. + +Pl. 34, Fig. 1. + +In the specimen figured, the outline is exactly elliptical, although the +species is usually conical at one end. + + +SURIRELLA GEMMA EHR. + +Valve ovate or ovate-elliptical, rounded at each end, sometimes +asymmetrical along the longitudinal axis; pseudoraphe very narrow; costae +distant, at irregular intervals, about 2 in 10 [mu], somewhat radiate, +reaching the pseudoraphe; striae, 20 in 10 [mu], punctate. Frustule in zone +view cuneate. L. 70-120 [mu]. + +Along the coast. + +Pl. 36, Fig. 4. + + +SURIRELLA TENERA GREG. + +Valve ovate; pseudoraphe narrow, well-defined; costae indistinct, 2-1/2 in +10 [mu], their margins invisible; striae about 14 in 10 [mu], punctate, +more evident near the margin. L. 90 [mu]. + +_Surirella diaphana_ Bleisch. + +Pavonia, N. J., artesian well. + +Pl. 35, Fig. 6. + +The figure is that of the var. nervosa A. S. (Atlas, Pl. 23, Fig. 15), +which differs from the type in having the position of the costae indicated +by scattered puncta. + + +{126}SECTION 2 + +SURIRELLA GUATIMALENSIS EHR. + +Valve ovate; pseudoraphe very narrow and indistinct; costae short, +marginal, 2-2-1/2 in 10 [mu], absent from the rounded end. L. 120 [mu]. + +_Surirella cardinalis_ Kitton. + +Smith's Island, Delaware River. + +Pl. 36, Fig. 5. + + +SURIRELLA OVALIS BREB. + +Valve ovate; costae short, marginal, radiate, 3-6 in 10 [mu], often +unequal; central area ovate, indistinctly costate; striae scarcely visible, +about 18 in 10 [mu]; pseudoraphe narrow. L. 45-93 [mu]. + +_Surirella davidsonii_ A. S. + +Fresh or brackish water. + +Pl. 35, Fig. 5; Pl. 39, Fig. 11. + +The smaller specimen is from the Delaware River, and the larger from the +Hudson River. + + +SURIRELLA CRUMENA BREB. + +Valve nearly orbicular; costae short, marginal, radiate; pseudoraphe +narrow, indistinct; central area indistinctly costate, sometimes +interrupted. + +On account of the extreme confusion in the names of many forms which appear +to be variations of S. ovalis, I have followed Van Heurck in retaining the +original names as specific. De Toni gives S. crumena as a variety of S. +ovalis. + +Fresh and brackish water. Quite common in the Delaware River. + +Pl. 35, Fig. 4. + + +SURIRELLA PINNATA WM. SM. + +Valve ovate or oblong-ovate; costae reaching the linear pseudoraphe, about +6 in 10 [mu]. L. 40 [mu]. + +_Surirella ovalis_ var. _pinnata_ (Wm. Sm.) De Toni. + +S. pinnata is the type of a number of small forms usually found together, +including S. panduriformis, S. angusta and S. minuta. + +Fresh water. Media (Palmer). + +Pl. 36, Fig. 7; Fig. 9 (abnormal). + +Var. minuta, a small form of S. pinnata, occurs with the type. + + +SURIRELLA PANDURIFORMIS WM. SM. + +Valve linear-oblong, with rounded ends, more or less constricted in the +middle; otherwise as in S. pinnata. L. 54 [mu]. + +Fresh water. + +Pl. 36, Fig. 6. + + +{127}SURIRELLA ANGUSTA KUETZ. + +Valve linear, with cuneate ends; otherwise as in S. pinnata. + +Fresh water. + +Pl. 36, Fig. 8. + +S. pinnata, S. panduriformis, and S. angusta have a narrow central area, +and differ from S. ovalis which has short costae. + + +SURIRELLA OBLONGA EHR. ? + +Valve elliptical-lanceolate, with obtuse ends; costae, marginal, 2-1/2 in +10 [mu]; median area granulate; pseudoraphe narrow, lanceolate, scarcely +visible; striae about 18 in 10 [mu]. L. 60 [mu]. + +Blue clay. Rare. + +Pl. 35, Fig. 9. + +This has the outline and appearance of S. oblonga Ehr. (Mik. Pl. 15, Fig. +48), but the costae are closer. + + +SURIRELLA RECEDENS A. S. + +Valve ovate; costae, 2-2-1/2 in 10 [mu]; pseudoraphe narrow, not reaching +the ends of the valve; intercostal spaces more evident near the middle. L. +50 [mu]. + +Blue clay. Not uncommon. + +Pl. 35, Fig. 7. + + +SURIRELLA CRUCIATA A. S. + +Valve ovate; pseudoraphe very narrow; costae, 2 in 10 [mu]; the outline of +several of the median costae strongly emphasized, while the other costae +are indistinct. L. 54 [mu]. + +Blue clay. + +Pl. 35, Fig. 10. + + +SURIRELLA GRACILIS GRUN. + +Valve linear, with sub-cuneate ends, slightly constricted in the middle; +pseudoraphe very narrow; costae, 6-7 in 10 [mu]; transverse striae about 26 +in 10 [mu], punctate. L. 75 [mu]. + +According to De Toni (p. 598), this form is a Nitzschia. It has, however, a +narrow pseudoraphe. + +Pavonia, N. J., artesian well. Rare. + +Pl. 35, Fig. 11. + + +SECTION 3 + +SURIRELLA FASTUOSA EHR. + +Valve ovate; costae about 1-2 in 10 [mu], dilated at the margin and +contracting at about one-fourth the distance toward the middle; area, +ovate-lanceolate; pseudoraphe, narrow and indistinct; intercostate striae +more evident near the margin, 19 in 10 [mu], becoming again evident in a +narrow band about one-half the distance to the pseudoraphe. L. 50-120 [mu]. + +Along the coast. More common southward. + +Pl. 35, Fig. 1. + + +{128}SURIRELLA FEBIGERII LEWIS + +Valve ovate-lanceolate; costae about 2-1/2 in 10 [mu] with punctate +interspaces extending half the distance toward the median hyaline area, +which is divided longitudinally on each side of the narrow pseudoraphe by +two longitudinal bands composed of short, transverse, irregular, punctate +lines. + +Along the coast. + +Pl. 36, Fig. 3. + + +SECTION 4 (STENOPTEROBIA) + +SURIRELLA ANCEPS LEWIS + +Frustule linear, straight or nearly so; valve sigmoid with rounded apices; +costae marginal, nearly obsolete; striae distinct, about 15 in 10 [mu]; +pseudoraphe wide. L. to 320 [mu]. + +Hammonton Pond and Tom's River, N. J. + +Pl. 34, Fig. 2. + + +SURIRELLA INTERMEDIA LEWIS + +Frustule linear, straight, widened at the truncate ends; valve linear, +sigmoid, tapering to the sub-acute ends; costae about 5 in 10 [mu]; striae +about 20 in 10 [mu]. L. variable. + +Hammonton Pond, N. J. + +Pl. 34, Fig. 3; Pl. 39, Fig. 9 (zone view). + +This, perhaps, is forma sub-acuta Fricke. + +Fig. 7, Pl. 34, is probably a small form of S. intermedia, from Willistown, +Pa. It resembles a Nitzschia. + + +SURIRELLA DELICATISSIMA LEWIS + +Frustule linear, rounded at the ends; valve linear-lanceolate, sometimes +very slightly constricted in the middle, with acute apices; costae, 5 in 10 +[mu]; striae about 20 in 10 [mu]; pseudoraphe well defined, lanceolate. L. +to 90 [mu]. + +Fresh water. Newtown Square. + +Pl. 34, Figs. 5 and 6 (small forms). + + +SURIRELLA ARCTISSIMA A. S. + +Valve linear, tapering to the sub-acute ends; costae marginal, 5 in 10 +[mu]; striae, 18 in 10 [mu]; pseudoraphe not evident. L. 184 [mu]. + +May's Landing, N. J. + +Pl. 34, Fig. 4. + +Fig. 10, Pl. 39, is a small form from Newtown Square, Pa., in which the +length is 86 [mu], the costae 5 and the striae 16 in 10 [mu]. + + +PODOCYSTIS KUETZ. (1844) + +(pous, a foot, and cystis, a bag) + +Frustules cuneate, similar to Surirella, but attached by short stipes to +other algae; valve obovate. + + +{129}PODOCYSTIS ADRIATICA KUETZ. + +Valve nearly symmetrical, obovate, with transverse costae about 4 in 10 +[mu], alternating with double rows of coarse puncta; median line distinct, +linear. L. 43 [mu]. + +_Podocystis americana_ Bail. + +Hell Gate, N. Y. + +Pl. 40, Fig. 6. + + +CYMATOPLEURA WM. SM. (1851) + +(cuma, a wave, and pleura, a side) + +Valve elliptical; surface transversely undulate, with short, marginal +costae. Frustule in zone view linear, with undulated sides. + +Auxospore formation as in Surirella. + + +CYMATOPLEURA SOLEA (BREB.) WM. SM. + +Valve oblong, with cuneate apices, constricted in the middle; costae about +6 in 10 [mu]; striae, 10 in 10 [mu]; pseudoraphe scarcely visible. L. +50-300 [mu]. + +Blue clay. Common in the Hudson River. + +Pl. 34, Figs. 8 and 9. + + +CYMATOPLEURA ELLIPTICA (BREB.) WM. SM. + +Valve elliptical; marginal costae short, 3 in 10 [mu]; striae delicate, 18 +in 10 [mu]; undulations four or more. L. 70-140 [mu]. + +Blue clay. + +Pl. 37, Fig. 1. + +_Forma spiralis._--Valve ovate, swelled into curved ridges at the lower +end, with a contraction of the valve. + +Port Penn, Delaware River. + +Pl. 37, Fig. 2. + + +CYMATOPLEURA MARINA LEWIS + +Frustule linear, with numerous undulations, ends apiculate; valve +linear-lanceolate, with acute ends; striae transverse, punctate at unequal +intervals, from 16-18 in 10 [mu]. L. 43 [mu]. + +East River, N. Y. + +Pl. 37, Figs. 3 and 4. + +Lewis states that the ends are more or less truncate. I do not find them +so. + + +CAMPYLODISCUS EHR. (1841) + +(campulos, curved like a saddle) + +Valve orbicular or sub-orbicular, with costae or punctate rays converging +from the circumference toward the hyaline centre, which sometimes appears +like a pseudoraphe. Frustule of two saddle-shaped valves at right angles to +each other. The zone view may be of almost any shape according to position. + +Endochrome consists of two bands, each lining the inner surface of each +valve. Auxospore and conjugation unknown. + + +{130}CAMPYLODISCUS ECHENEIS EHR. + +Valve sub-orbicular, saddle-shaped; costae indistinct, short, marginal; +rows of round or elongated puncta converge toward the lanceolate, hyaline +median space. Diam. 80-140 [mu]. + +_Campylodiscus argus_ Bail. + +Blue clay. Reservoir at Thompson and Twenty-sixth Sts., Phila. + +Pl. 37, Fig. 6. + +This form, usually considered as brackish and marine, is occasionally found +in fresh water. According to Deby, it is fossil in the "Champlain deposit +of N. A." + + +CAMPYLODISCUS HIBERNICUS EHR. + +Valve irregularly orbicular; costae, 40-60, about 2 in 10 [mu], wide at the +margin and attenuated toward the centre which is somewhat quadrate; the +radials rough with minute apiculi. + +Pensauken, N. J., artesian well. + +Pl. 37, Fig. 5. + + + +{131}APPENDIX + + +COLLECTION AND PREPARATION OF DIATOMS + +It is assumed that every student of the Diatomaceae has a general knowledge +of the collection, preparation, mounting and examination of material. For +the novice, however, the following methods, used by the author for many +years, may be of service. + +_Collection of Fresh-water Material._--The yellow film on the inside of +aquaria always contains small species. Stems of water-plants near the +shores of ponds and the submerged roots, the brownish coating of rocks in +streams and water-falls, fountains, and water-troughs, are prolific. At all +times of the year, some diatoms may be found in a thin layer upon the mud +of rivers or creeks. In the spring, brown patches of mud, filled with +bubbles, floating near the shore in ponds, or coming down with the current +in rivers, are rich in various forms. Within the limits assigned to our +district, I have made collections in the following localities: Schuylkill +River, including the region near Fairmount Dam, several reservoirs and the +water-supply; the Wissahickon and Fairmount Park, Darby, Crum and Ridley +Creeks, the Neshaminy and the Brandywine; meadow pools and rivulets near +the city; the upper Delaware, the Water Gap and numerous cascades +northward; the Shawangunk Mountains and the Poconos; many parts of New +Jersey along the coast; the Pine Barren region, the Hammonton, Atsion and +Kirkwood Ponds and the swamps near Atco. + +In the collection of fresh-water material, it is well to be provided with a +number of small bottles. Take a handful of the water-plants or algae, and +squeeze the material into the bottles, or, lacking a bottle, wrap it in +paper. With a small forceps it is possible to detach minute quantities of a +pure gathering which may not need further preparation beyond burning to a +red heat on the cover-glass before mounting. A malacca cane, with extending +rod to which may be screwed a bottle, net, spoon or hook, is useful on a +long trip. If it is impossible to separate the thin film of diatoms from +the mud in the bed of streams, dip up the surface mud with one bottle, +allow to settle a few minutes, then pour off the supernatant liquid, which +will be comparatively free from sand, into another bottle. It must be +confessed, however, that the mud in streams near Philadelphia contains a +large quantity of fine mica which, in some instances, it is impossible to +remove. + +_Collection of Marine Material._--Shell scrapings, the stomachs of fish, +marine algae, especially the brown and red algae, the hulls of vessels, mud +from anchors and dredgings, are all sources which may prove valuable. In +the sand ripples, after the tide recedes, a yellowish-brown deposit will be +noticed. This should be taken up carefully with a spoon and placed in a +bottle; the sand will settle at once and a very pure gathering will be held +in suspension in the water. Such collections may be made along the entire +coast of New Jersey on sunny days in summer. In salt meadows near Absecon +and Hackensack, large quantities of diatoms, including Pleurosigma, may be +obtained in the yellow scum floating on the surface. + +_The Blue Clay Deposit._--The blue clay occurs as a pre- or post-glacial +deposit in the bed of the ancient Delaware River, and, at depths varying +usually from fifteen to forty feet below the surface, has been obtained +from artesian wells at Pavonia, Pensauken and Gloucester, N. J., also at +Port Penn on the Delaware, and especially from the dredgings {132}made by +the removal of Smith's Island opposite the city. In the city proper, it may +be stated briefly that material may be found in a stratum of very light +blue clay at a depth varying from twenty to sixty feet in many places south +of Arch St. east of Broad St., and also along the beds of ancient rivulets +near Tioga St., at Sixteenth St., and in certain other places which were +probably subject to tidal overflow. One of the best collections was made +along the bank of the Schuylkill at the east end of Walnut St. Bridge, at a +depth of thirteen feet below the surface. Excavations for the Reading +Terminal and the Subway and several buildings, as the Bingham House, have +furnished numerous specimens. + +_Cleaning the Material._--Some gatherings may be so pure as to be ready for +mounting when treated with dilute alcohol and oil of cloves. If, when +gathered, the diatoms are immersed in a saturated solution of picric acid +for several days, they may be stained with carmine or methylene blue, or +whatever may be required to emphasize the contents of the frustules, +including the endochrome and the pyrenoids. After staining, pass as rapidly +as expedient through the treatment with dilute alcohol and oil of cloves, +and mount in benzol balsam, avoiding heat. A hot solution of mercuric +bichloride is sometimes used for the preservation of the endochrome, +although washing is needed before mounting. For the particular stain +considered best for certain details of structure, it will be advisable to +consult works on Micro-Chemistry or Heinzerling (_l. c._). The stains of +most importance are carmine, methylene blue, haematoxylin, gold chloride +and Bismarck brown. + +Whatever method may be used in staining, the identification of forms is +impossible, in most cases, unless the valves are carefully cleaned and the +cell-contents destroyed. For this purpose provide a casserole holding from +five to eight ounces, an iron tripod stand with alcohol lamp, several +six-inch test-tubes, preferably those with a standard base, fitted with +pure rubber corks. Take the material as free from twigs, dead leaves, sand, +and other matter as possible, place it in the casserole, and add about the +same quantity of nitric acid. Boil for twenty minutes and then add about +half a teaspoonful of powdered bichromate of potash, stirring with a glass +rod. Then take a beaker-glass partly filled with water and pour into it +slowly the liquid which has been allowed to cool a short time, whirling the +casserole to cause the concentration of sand in the centre. Allow the +material to settle for half an hour or longer, according to the amount of +diatoms and their size. Pour off the water, add more water, and place in a +test-tube. Repeat the decantation, shaking the test-tube, closed with a +rubber cork, vigorously each time. From time to time whirl the diatoms in +the casserole and throw away the sand collected in the centre. By repeating +the decantation, shaking and whirling, the deposit will be found to consist +almost entirely of diatoms. It may be necessary to repeat the boiling in +the acid and bichromate. If, however, any detritus other than sand is +noted, boil in sulphuric acid and add from time to time minute pinches of +powdered chlorate of potash, being careful to protect the eyes by holding a +piece of glass before them; otherwise the explosions which occur are likely +to throw some of the boiling acid into the eyes and destroy the sight. The +material, when clean, should be white or, in the case of Synedra, +yellowish. It is quite easy to construct a box fitted with the proper +apparatus for boiling and provided with a glass door for observation, and a +method of introducing the chlorate of potash through a small aperture or +tube. The box may be placed in the garden or fastened outside of a window +so that the poisonous fumes may be carried off. + +An excellent method, in the case of larger forms, is to boil the material +already cleaned by the acid in water to which a few shavings of coarse +brown soap are added. The difference in density will hold in suspension any +flocculent matter, and while many of the smaller {133}forms will not +settle, the others will be perfectly cleaned. When satisfied with the +cleaning, preserve the stock material in part alcohol and, in using, pour +into a smaller bottle the amount required, replace the dilute alcohol with +distilled water, and mount as directed. It often happens that gatherings +are made consisting almost entirely of sand. Attempts at cleaning in the +usual way will cause the loss of nearly all of the diatoms. In this case, +after the material has been treated with acid until nothing remains but +sand and a few diatoms, the mechanical finger must be used. + +In the cleaning of marine deposits, various methods may be required. In the +case of partly siliceous species, washing in pure water repeatedly is all +that can be done. The larger and heavier diatoms may be separated from the +sand by elutriation or by whirling in a casserole, by rocking in a shallow +dish the shape of a watch crystal, or by pouring slowly over a strip of +plate-glass at least two feet in length inclined at an angle of thirty +degrees. The sand will cling to the glass, while the greater portion of the +diatoms will run off. Where particles of shells or foraminifera are +present, a preliminary boiling in hydrochloric acid is advisable. In all +marine gatherings, the salt should first be washed out before proceeding +with the cleaning. + +For hardened masses of clay and for fossil deposits, it is necessary to +boil in carbonate of soda and follow with the acid treatment. Citric acid +and acetate of potash used alternately in boiling may be tried. Soaking for +a time in acetate of potash and allowing the material to deliquesce for a +week before further process, has proved successful in some instances. The +repetition of several methods and the gentle breaking of the harder masses +with the point of a needle will disintegrate almost any diatomaceous earth, +but, as a last resort for refractory deposits, boil in pure water, add a +piece of caustic potash about the size of a pea, continue the boiling not +more than thirty seconds longer, and pour instantly into dilute +hydrochloric acid; otherwise the diatoms will be destroyed. Afterwards +proceed with the usual treatment. + +_Slides and Covers._--Take half an ounce of No. 1 covers, circles, and +place them in a wide-mouthed bottle. Add a portion of the following mixture +(Dr. Carl Seiler's formula): + + Bichromate of potash 2 oz. + Sulphuric acid 3 fl. oz. + Water 25 fl. oz. + +Shake the bottle in order that the surfaces of the covers may be fully +exposed to the action of the acid, and set aside for several hours. Decant +the solution, add water repeatedly until all traces of the mixture are +removed, and keep the circles in the bottle in fifty-per cent. alcohol. +When needed, take out a circle with forceps and dry on a linen cloth. + +The slides may be treated in the same way, or they may be easily prepared +by immersion in a solution of washing soda, and then washed and dried. This +process may be used in cleaning the balsam or styrax from old slides. + +_Preparation of Strewn Mounts._--Place several covers on the mounting +stand. With a dipping tube, cover each circle with distilled water, and add +a small drop of the prepared diatoms, being careful to avoid any vibration +of the stand. Heat the stand until small bubbles begin to appear, remove +the lamp, and allow the water to evaporate. If the above method is +carefully followed, the diatoms will be deposited in an even layer, +provided the material is not too dense. Take a slide, centre it, and place +a small amount of styrax on the centre. Invert the prepared cover, and +gently place it upon the styrax. Heat the slide {134}on the mounting stand +until the styrax bubbles and then allow to cool. If bubbles still remain, +heat again until they disappear. It is well to mount several slides more +than required, as some may be imperfect. + +_Preparation of Selected Mounts._--Take a slide, place a minute quantity of +beeswax on two places at a distance apart nearly equal to the diameter of +the cover used. Place a cover on the wax and press it down flat, or +sufficiently to keep it in position. Dip a fine needle into the following +cement: + + Glacial acetic acid 12 drachms + Gelatine 2 drachms + Alcohol 1 drachm + +This is made by adding the acid to the gelatine in a water-bath and then +the alcohol, and filtering. Apply the moistened needle to the centre of the +cover and spread as small a quantity as possible in a thin layer. Now place +the slide upon the turn table, centre it with respect to the position of +the gelatine, and with the finest sable brush draw a circle about a tenth +of an inch in diameter around the gelatine in water-color (Windsor), blue +or vermilion, or in India ink. Instead of the water-color, a circle of +tin-foil the size of the cover and pierced with a hole in the centre may be +used, but the colored circle is to be preferred, as, when brought into +view, it indicates exactly the focus required for observing the diatom. + +The bottle containing the cleaned material, which has been kept in water +and alcohol, should be refilled with distilled water and well shaken, when +a small portion may be taken up with a dipping tube and evenly distributed +over a portion of a slide and then dried. By the use of a mechanical +finger, fitted with a small piece of finely spun glass attached by wax to +the holder of the finger, when the microscope is focussed until the glass +thread touches the diatom selected, it will adhere to the thread. Raise the +body of the microscope, remove the slide containing the spread material, or +move it to another part of the stage, and place the slide with the prepared +cover in the same position. Now carefully lower the body-tube of the +instrument until the diatom rests upon the gelatine, breathe gently upon +it, remove the cover from the slide, invert it over another slide +containing a drop of styrax and proceed by heating to mount as before. The +size of the diatom, the amount of gelatine, and several other factors, will +enter into the question of success or failure. I have, however, employed +the above method and have mounted thousands of slides of selected diatoms +successfully. It is necessary to avoid any air current which will cause the +diatom to fall from the thread. On very cold days the glass thread +sometimes becomes electrified and the diatoms will not stick; on sultry +days in August in our locality the diatoms will stick too closely. + +By the same method, slides of arranged diatoms can be made using a glass +circle properly marked with lines in the eye-piece. Care should be taken to +use glass threads more or less in proportion to the size of the diatoms. A +cat's whisker is preferred by some to the glass thread. It has the +advantage of not breaking, but unless it is quite short it is too flexible. +If the point of the thread becomes covered with gelatine, lower it into a +minute drop of water upon a separate slide, and by moving it about it will +be cleaned. The diatom itself may be washed in the same way, if it is not +too small. + +_Instruments Required._--For collecting, in order to determine the quality +of the find, any simple lens of fifteen to twenty diameters is sufficient. +A Stanhope is quite useful {135}although difficult to obtain, while an +achromatic triplet of sufficient power will probably be all that is +necessary. For selecting with the mechanical finger, an objective of +two-thirds-inch focus is the most convenient, but for determining species a +one-fifth-inch is needed, an immersion objective being essential for minute +forms. + +No particular form of microscope is required. Any instrument having +standard parts, inclination of the body to the axis, a sub-stage condenser +and movable stage, will prove serviceable in nearly all investigations. For +critical work, measurement of striae and location of specimens on the +slide, the large models of Bausch and Lomb leave nothing to be desired. One +smaller instrument may be used for rapid examination and for selection with +the mechanical finger. If the stage is supplied with a vernier, the diatoms +can be located rapidly and recorded for future reference. The Zentmayer +Army Hospital stand with mechanical stage is excellent. The Continental +stands, convenient for laboratory work, especially in the examination of +bacteria, are not so serviceable as the larger stands of American and +English make. The stand especially designed by Dr. Henri Van Heurck, the +celebrated Belgian naturalist, is, without doubt, admirably suited to the +investigation of the Diatomaceae. In the form of the Circuit Stage as made +by Watson and Sons, of London, supplied with proper condenser and +mechanical stage with vernier attachment, it has been used in the +preparation of the present work with much satisfaction. + +The drawings have all been made with an Abbe camera lucida, a 3 mm. +objective and a No. 10 eye-piece, producing a magnification of about 800 +diameters. All illustrations are from actual specimens in my cabinet or, in +a few instances, from slides sent me by friends. In the measurement of +striae and puncta, the number in ten microns is stated, and will be found +to be approximately correct in most of the drawings, except when the number +is in excess of twenty in ten microns, in which case it is impossible to +represent the markings accurately on figures of the magnification adopted. +All drawings are from specimens in this locality, except in a few cases +mentioned in the text. + + + + +{137}INDEX + + +(SYNONYMS IN ITALICS) + + + + PAGE + Achnanthes, 58 + brevipes Ag., 59 + coarctata (Breb.) Grun., 59 + danica (Floegel) Grun., 60 + exigua Grun., 59 + inflata (Kuetz.) Grun., 59 + lanceolata (Breb.) Grun., 59 + linearis forma curta H.L.S., 59 + longipes Ag., 58 + subsessilis Kuetz., 59 + + Actinella, 54 + punctata Lewis, 54 + + Actinocyclus, 26 + barkleyi var. aggregata Rattr., 27 + ellipticus var. delawarensis n. var., 27 + moniliformis Ralfs, 27 + + Actinoptychus, 24 + _cellulosa_ Ehr., 24 + heliopelta Grun. var.?, 25 + _omphalopelta_ Ehr., 24 + undulatus (Kuetz.) Ralfs, 24 + vulgaris var. interrupta n. var., 24 + + Amphipleura, 78 + pellucida Kuetz., 78 + rutilans (Trentepohl) Cl., 78 + + Amphiprora, 68 + alata Kuetz., 68 + conspicua Grev., 68 + _lepidoptera_ Greg., 69 + ornata Bail., 68 + paludosa Wm. Sm., 68 + pulchra Bail., 68 + + _Amphitetras_, + _antediluviana_ Ehr., 32 + _tessellata_ Shad., 32 + + Amphora, 65 + acuta Greg., 66 + angusta var. eulensteinii Grun., 67 + _aponina_ Kuetz., 66 + arenaria Donk., 67 + areolata Grun., 66 + coffaeiformis (Ag.) Kuetz., 66 + crassa Greg., 65 + _eulensteinii_ A.S., 67 + gigantea var. fusca A.S., 65 + _insecta_ Grun., 69 + laevis Greg., 66 + lineolata Ehr., 66 + _mucronata_ H.L.S., 69 + obtusa Greg., 67 + ocellata var. cingulata Cl., 67 + ostrearia Breb., 66 + ovalis (Breb.) Kuetz., 65 + var. libyca (Ehr.) Cl., 65 + var. pediculus (Kuetz.) Cl., 65 + _plicata_ Greg., 66 + _porcellus_ Kitton, 66 + proteus Greg., 65 + _quadrata_ Breb., 66 + robusta Greg., 65 + _salina_ Wm. Sm., 66 + _vitraea_ Cl., 66 + + Anomoeoneis, 80 + follis (Ehr.) Cl., 80 + serians Breb., 80 + sphaerophora (Kuetz.) Cl., 80 + + Anorthoneis, 56 + excentrica (Donk.) Grun., 56 + + Asterionella, 50 + formosa Hass., 50 + inflata Heib., 50 + + Attheya, 38 + decora West, 38 + + Aulacodiscus, 26 + argus (Ehr.) A.S., 26 + + Auliscus, 28 + caelatus Bail., 29 + pruinosus Bail., 28 + punctatus Bail., 28 + sculptus (Wm. Sm.) Ralfs, 29 + _spinosus_ Christian, 29 + + Auricula, 69 + _insecta_ (Grun.) Cl., 69 + mucronata (H.L.S.) Per., 69 + + _Bacillaria_, 119 + _paradoxa_ Gmelin, 119 + + Biddulphia, 31 + alternans (Bail.) V. H., 33 + antediluviana (Ehr.) V. H., 32 + biddulphiana (Smith), 31 + favus (Ehr.) V. H., 31 + granulata Roper, 32 + laevis Ehr., 33 + _pulchella_ Gray., 31 + reticulum (Ehr.), 33 + rhombus (Ehr.) Wm. Sm., 32 + smithii (Ralfs) V. H., 32 + turgida (Ehr.) Wm. Sm., 32 + + Brebissonia, 79 + boeckii (Kuetz.) Grun., 79 + palmerii n. sp., 80 + + Caloneis, 81 + brevis var. vexans Grun., 82 + formosa (Greg.) Cl., 82 + liber (Wm. Sm.) Cl., 81 + permagna (Bail.) Cl., 82 + var. lewisiana n. var., 82 + powellii (Lewis) Cl., 83 + silicula (Ehr.) Cl., 81 + var. inflata (Grun.) Cl., 81 + trinodis (Lewis), 81 + wardii Cl., 82 + + Campylodiscus, 129 + _argus_ Bail., 130 + echeneis Ehr., 130 + hibernicus Ehr., 130 + + _Cerataulus_ + _smithii_ Ralfs, 32 + _turgidus_ Ehr., 32 + + Cocconeis, 57 + dirupta Greg., 58 + pediculus Ehr., 57 + pellucida Grun., 58 + placentula Ehr., 57 + var. lineata (Ehr.) V. H., 58 + scutellum Ehr., 57 + var. ornata Grun., 57 + + _Cocconema_ + _asperum_ Ehr., 61 + + _Colletonema_ + _neglectum_ Thwaites, 95 + _vulgaris_ Thwaites, 77 + + _Conferva_ + _biddulphiana_ Smith, 31 + _flocculosa_ Roth, 36 + _moniliformis_ Mueller, 16 + _nummuloides_ Dillw., 1617 + _rutilans_ Trentepohl, 78 + + Coscinodiscus, 21 + argus Ehr., 23 + asteromphalus Ehr., 23 + var. omphalantha Grun., 23 + biangulatus A. S., 23 + denarius A. S., 22 + excentricus Ehr., 21 + var. perpusilla Grun., 21 + lewisianus Grev., 24 + lineatus Ehr., 21 + marginatus Ehr., 22 + _minor_ Wm. Sm., 14 + nitidulus Grun., 21 + nitidus Greg., 21 + oculus-iridus Ehr., 23 + polyacanthus Grun., 22 + radiatus Ehr., 23 + _striatus_ Kuetz., 19 + subaulacodiscoidalis Rattr., 23 + subtilis Ehr., 21 + velatus Ehr., 22 + + _Creswellia_ + _turris_ Grev., 18 + + Cyclotella, 19 + antiqua Wm. Sm., 20 + comta (Ehr.) Kuetz., 20 + _dallasiana_ Wm. Sm., 19 + _kuetzingiana_ Wm. Sm., 19 + meneghiniana Kuetz., 19 + var. stelligera Cl. and Grun., 20 + var. stellulifera Cl. and Grun., 20 + operculata (Ag.) Kuetz., 20 + _scotica_ Kuetz., 18 + striata (Kuetz.) Grun., 19 + stylorum (Br.?) V. H., 20 + + Cymatopleura, 129 + elliptica (Breb.) Wm. Sm., 129 + marina Lewis, 129 + solea (Breb.) Wm. Sm., 129 + + Cymbella, 60 + affinis Kuetz., 61 + amphicephala Naegeli, 61 + aspera (Ehr.) Cl., 61 + cistula (Hempr.) Kirchn., 62 + cuspidata Kuetz., 60 + cymbiformis (Kuetz.) Breb., 62 + ehrenbergii Kuetz., 60 + excisa (Kuetz.) De Toni, 61 + _gastroides_ Kuetz., 61 + gracilis (Rab.) Cl., 64 + heteropleura (Ehr.) Kuetz., 60 + lacustris (Ag.) Cl., 64 + lanceolata (Ehr.) Kirchn., 62 + mexicana (Ehr.) A. S., 62 + naviculiformis Auerswald, 60 + parva (Wm. Sm.) Cl., 61 + philadelphica n. sp., 63 + prostrata (Berk.) Cl., 63 + rhomboidea n. sp., 63 + sinuata Greg., 61 + triangulum (Ehr.) Cl., 63 + tumida (Breb.) V. H., 62 + turgida (Greg.) Cl., 63 + var.?, 63 + ventricosa Kuetz., 62 + + Diatoma, 41 + anceps (Ehr.) Kirchn., 42 + _arcuatum_ Lyng., 35 + _biddulphianum_ Ag., 31 + hiemale (Lyng.) Heib., 42 + _marinum_ Lyng., 37 + vulgare Bory., 42 + var. elongatum (Ag.), 42 + var. grande (Wm. Sm.) Grun., 42 + + Dictyoneis, 78 + marginata var. commutata Cl., 79 + var. maxima n. var., 79 + var. typica Cl., 78 + + Dimerogramma, 46 + marinum (Greg.) Ralfs, 46 + minus (Greg.) Ralfs, 47 + _sinuatum_ Thwaites, 119 + surirella (Ehr.) Grun., 46 + + Diploneis, 84 + campylodiscus (Grun.) Cl., 86 + crabro Ehr. var.?, 85 + var. expleta (A. S.) Cl., 85 + var. pandura (Breb.) Cl., 85 + var. pandurella Cl.?, 85 + elliptica (Kuetz.) Cl., 84 + var. _minutissima_ Grun., 85 + excentrica n. sp., 85 + fusca var. delicata (A. S.) Cl., 85 + gemmata (Grev.) Cl., 86 + gruendleri (A. S.) Cl., 85 + oculata (Breb.) Cl., 86 + puella (Schum.) Cl., 85 + smithii (Breb.) Cl., 84 + + Ditylum, 30 + intricatum (West) Grun., 30 + + _Echinella_ + _circularis_ Grev., 40 + _flabellata_ Carm., 39 + _paradoxa_ Lyng., 39 + + Encyonema, 62 + + Epithemia, 111 + argus Kuetz., 111 + var.?, 111 + _gibba_ var. _ventricosa_ Kuetz., 113 + gibberula var. producta Grun., 112 + _marina_ Donk., 114 + muelleri A. S.?, 111 + musculus Kuetz., 112 + var. constricta (Breb.) V. H., 112 + _succincta_ Breb., 112 + turgida (Ehr.) Kuetz., 111 + zebra var. proboscidea (Kuetz.) Grun., 112 + + Eunotia, 51 + bactriana Ehr., 54 + biceps Ehr., 53 + bidentula Wm. Sm., 54 + _bigibba_ Greg., 53 + formica Ehr. var.?, 54 + gracilis (Ehr.) Rab., 51 + hemicyclus (Ehr.) Ralfs, 53 + _incisa_ Greg., 52 + luna Ehr., 52 + lunaris (Ehr.) Grun., 53 + major (Wm. Sm.) Rab., 51 + nymanniana Grun., 51 + pectinalis (Kuetz.), 52 + var. solierolii (Kuetz.), 52 + var. undulata Ralfs, 52 + var. ventricosa Grun., 52 + praerupta Ehr., 53 + var. bidens Grun., 53 + robusta Ralfs, 53 + veneris Kuetz., 52 + + Eunotogramma, 33 + laeve Grun., 33 + + Euodia, 34 + gibba Bail., 34 + + Eupodiscus, 28 + _argus_ (Ehr.) Wm. Sm., 26 + radiatus Bail., 28 + _radiatus_ Wm. Sm., 32 + + Fragilaria, 44 + arctica Grun., 44 + capucina var. mesolepta Rab., 45 + construens (Ehr.) Grun., 45 + harrisonii (Wm. Sm.) Grun., 45 + linearis Cstr., 45 + parasitica (Wm. Sm.), 45 + undata Wm. Sm., 44 + virescens Ralfs, 44 + + Frustulia, 77 + _acuminata_ Kuetz., 76 + interposita (Lewis) De Toni, 78 + lewisiana (Grev.) De Toni, 77 + rhomboides (Ehr.) De Toni, 77 + var. amphipleuroides Grun., 77 + var. saxonica Rab., 77 + vulgaris (Thwaites) De Toni, 77 + + Gaillonella, 16 + _crenulata_ Ehr., 15 + _granulata_ Ehr., 15 + _moniliformis_ Bail., 16 + nummuloides (Dillw.) Bory., 16 + _sulcata_ Ehr., 15 + + _Gloeonema_, 63 + _triangulum_ Ehr., 63 + + Gomphoneis, 70 + herculaneum (Ehr.) Cl., 70 + mamilla (Ehr.) Cl., 70 + + Gomphonema, 70 + acuminatum, 71 + var. coronata (Ehr.) Cl., 71 + var. trigonocephala (Ehr.) Cl., 71 + var. turris (Ehr.) Cl., 71 + var. turris (Ehr.) Cl.?, 71 + aequale Greg., 72 + angustatum Kuetz., 72 + augur Ehr., 72 + brasiliense var. demerarae Grun.?, 73 + capitatum Ehr., 72 + capitatum var. herculaneum Ehr., 70 + constrictum Ehr., 72 + geminatum Lyng., 71 + _insigne_ Greg., 71 + intricatum Kuetz., 72 + lanceolatum var. insignis (Greg.) Cl., 71 + montanum Schum., 71 + olivaceum Lyng., 73 + parvulum var. micropus (Kuetz.) Cl., 73 + sarcophagus Greg., 72 + sphaerophorum Ehr., 72 + _subclavatum_ var. _montana_ Schum., 71 + _tinctum_ Ag., 40 + ventricosum Greg., 73 + + Grammatophora, 36 + angulosa var. hamulifera (Kuetz.) Grun., 37 + islandica Ehr., 37 + marina (Lyng.) Kuetz., 37 + var. subtilissima (Bail.) V. H., 37 + serpentina Ralfs, 37 + _subtilissima_ Bail., 37 + + Gyrosigma, 75 + acuminatum (Kuetz.) Cl., 76 + _attenuatum_ (Kuetz.) Cl., 75 + balticum (Ehr.) Cl., 75 + var. _similis_ (Grun.) Cl., 76 + fasciola (Ehr.) Cl., 77 + hippocampus (Ehr.), 75 + kuetzingii (Grun.) Cl., 76 + parkeri var. stauroneioides Grun., 75 + prolongatum (Wm. Sm.) Cl., 76 + scalproides (Rab.) Cl., 76 + simile (Grun.), 76 + spencerii var. nodifera Grun., 76 + strigilis (Wm. Sm.) Cl., 76 + + Hantzschia, 113 + amphioxys (Ehr.) Grun., 113 + var. major Grun., 114 + marina (Donk.) Grun., 114 + virgata (Roper) Grun., 114 + + _Himantidium_ + _pectinate_ Kuetz., 52 + + Homoeocladia, 123 + filiformis Wm. Sm., 123 + + Hyalodiscus, 17 + radiatus var. arctica Grun., 17 + scoticus (Kuetz.) Grun., 18 + stelliger Bail., 17 + subtilis Bail., 18 + + Licmophora, 38 + baileyi (Ehr.) Grun., 40 + ehrenbergii (Kuetz.) Grun., 40 + flabellata (Carm.) Ag., 39 + gracilis (Ehr.) Grun., 39 + var. elongata (Kuetz.) De Toni, 39 + lyngbyei (Kuetz.) Grun., 40 + ovulum Mer., 39 + paradoxa (Lyng.) Ag., 39 + _splendida_ Wm. Sm., 39 + tincta (Ag.) Grun., 40 + + Lysigonium, 16 + moniliforme (Muell.) Link, 16 + _nummuloides_ (Lyng.) O'Meara, 17 + varians (Ag.) De Toni, 17 + + Mastogloia, 86 + angulata Lewis, 87 + apiculata Wm. Sm., 87 + _braunii_ Grun., 87 + elegans Lewis, 87 + exigua Lewis, 87 + kinsmanii Lewis, 87 + lanceolata Thwaites, 87 + smithii Thwaites, 87 + + Meloseira, 14 + _borreri_ Grev., 17 + crenulata (Ehr.) Kuetz., 15 + distans (Ehr.) Kuetz., 14 + _gowenii_ A. S., 15 + granulata (Ehr.) Ralfs, 15 + _nivalis_ Wm. Sm., 14 + _nummuloides_ Ag., 16 + roeseana Rab., 15 + var. epidendron (Ehr.) Grun., 15 + sulcata Kuetz., 15 + undulata (Ehr.) Kuetz., 15 + _varians_ Ag., 17 + + Meridion, 40 + circulare (Grev.) Ag., 40 + _constrictum_ Ralfs, 41 + + _Micromega_ + _ramosissimum_ Ag., 95 + + Navicula, 89 + _affinis_ Ehr., 83 + americana Ehr., 98 + _amphibola_ Cl., 92 + _amphigomphus_ Ehr., 83 + anglica Ralfs, 96 + _angulata_ Quek., 74 + ardua Mann, 96 + _arenaria_ Donk., 95 + atomus Naegeli, 100 + bacillum Ehr., 98 + _baltica_ Ehr., 75 + brasiliensis var. bicuneata Cl., forma + constricta, 92 + crucigera (Wm. Sm.) Cl., 100 + cryptocephala Kuetz., 97 + cuspidata Kuetz., 100 + var. ambigua (Ehr.) Cl., 100 + cyprinus (Wm. Sm.), 95 + delawarensis Grun., 92 + dicephala Wm. Sm., 96 + _digito-radiata_ var. _cyprinus_ (Ehr.?) Wm. + Sm., 95 + elegans Wm. Sm., 101 + var. cuspidata Cl., 101 + _firma_ Kuetz., 84 + _fischeri_ A. S., 90 + _follis_ Ehr., 80 + fuchsii Pant., 91 + gastrum Ehr., 96 + _gigas_ A. S., 103 + _globiceps_ Lagerstedt, 96 + gracilis var. schizonemoides (Ehr.) V. H., 95 + grevillei (Ag.) Cl., 99 + hasta Pant., 97 + var. punctata n. var., 97 + hennedyi Wm. Sm., 93 + var. circumsecta Grun., 93 + var. manta A. S., 93 + _hippocampus_ Ehr., 75 + _hitchcockii_ Ehr., 84 + humerosa Breb., 91 + var. _elongata_ Pant., 91 + var. _fuchsii_ (Pant.) Cl., 91 + humilis Donk., 96 + _hungarica_ var. _capitata_ (Ehr.) Cl., 96 + inflexa Greg., 96 + integra Wm. Sm., 99 + _interposita_ Lewis, 78 + _iridis_ Ehr., 84 + irrorata Grev., 93 + lacustris Greg., 92 + lanceolata var. arenaria (Donk.) Cl., 95 + latissima Greg., 90 + var. elongata (Pant.) Cl., 91 + libellus Greg., 99 + _limosa_ Donk., 81 + longa (Greg.) Ralfs, 97 + lyra Ehr., 93 + var. dilatata A. S., 93 + var. ehrenbergii Cl., 93 + var.?, 93 + maculata (Bail.) Cl., 90 + _marginata_ Lewis, 78 + _marina_ Ralfs, 92 + minima Grun., 98 + _mormonorum_ Grun., 107 + mutica Kuetz., 97 + oblonga Kuetz., 97 + _oculata_ Breb., 86 + palpebralis Breb., 101 + pennata A. S., 96 + peregrina Ehr., 94 + pinnata Pant.?, 96 + placenta Ehr., 94 + praetexta Ehr., 92 + _producta_ Wm. Sm., 83 + punctata var. asymmetrica Lagerstedt, 92 + punctulata Wm. Sm., 92 + pupula var. bacillarioides Grun., 98 + pusilla Wm. Sm., 91 + var. subcapitata n. var., 91 + pygmaea Kuetz., 94 + radiosa Kuetz., 94 + ramosissima (Ag.) Cl., 95 + _rectangulata_ Greg., 110 + reinhardtii Grun., 95 + rhyncocephala Kuetz., 97 + salinarum Grun., 95 + semen Ehr., 98 + _silicula_ Ehr., 81 + _socialis_ Palmer, 104 + spectabilis var. emarginata Cl., 94 + _sphaerophora_ Kuetz., 80 + spicula (Hickie) Cl., 100 + _trochus_ Kuetz., 80 + tumida (Breb.) Cl., 99 + viridula var. rostellata Kuetz., 95 + yarrensis Grun., 101 + + Neidium, 83 + affine (Ehr.) Pfitzer, 83 + var. amphirhyncus (Ehr.) Cl., 83 + var. genuina forma maxima Cl., 83 + var. genuina forma minor Cl., 83 + amphigomphus (Ehr.) Pfitzer, 83 + hitchcockii (Ehr.) Cl., 84 + iridis (Ehr.) Cl., 84 + productum (Wm. Sm.) Cl., 83 + + Nitzschia, 114 + acicularis (Kuetz.) Wm. Sm., 123 + acuminata (Wm. Sm.) Grun., 117 + amphibis Grun., 122 + amphioxys Wm. Sm., 114 + apiculata (Greg.) Grun., 117 + bilobata Wm. Sm., 118 + circumsuta (Bail.) Grun., 118 + clausii Hantzsch, 121 + communis Rab., 122 + compressa Bail., 116 + var. minor H. L. S., 116 + _curvula_ Wm. Sm., 121 + dissipata (Kuetz.) Grun., 120 + dubia Wm. Sm., 118 + epithemioides Grun., 118 + fluminensis Grun., 120 + granulata Grun., 116 + insignis Greg., 119 + intermedia Hantzsch, 122 + linearis (Ag.) Wm. Sm., 122 + litoralis var. delawarensis Grun., 118 + longissima (Breb.) Ralfs, 123 + forma parva V. H., 123 + macilenta Greg., 120 + navicularis (Breb.) Grun., 116 + obtusa Wm. Sm., 121 + var. flexella H. L. S., 121 + var. scalpelliformis Grun., 121 + palea (Kuetz.) Wm. Sm., 122 + panduriformis Greg., 117 + var. minor Grun., 117 + _paradoxa_ (Gmelin) Grun., 119 + paxillifer (O. F. Mueller) Heib., 119 + plana Wm. Sm., 117 + _punctata_ (Wm. Sm.) Grun., 116 + reversa Wm. Sm., 123 + scalaris (Ehr.) Wm. Sm., 119 + sigma (Kuetz.) Wm. Sm., 121 + var. _curvula_ (Wm. Sm.) De Toni, 121 + sigmatella Greg., 121 + _sinuata_ var. _tabellaria_ (Grun.) V. H., 119 + spathulata Breb., 120 + spectabilis var. americana Grun., 122 + tabellaria Grun., 119 + tryblionella Hantzsch, 116 + vermicularis (Kuetz.) Hantzsch, 120 + + _Odontidium_ + _parasiticum_ Wm. Sm., 45 + _tabellaria_ Wm. Sm., 45 + + Opephora, 43 + pacifica (Grun.) Petit, 43 + pinnata var. lanceolata n. var., 44 + schwartzii (Grun.) Petit, 43 + + _Orthosira_ + _orichalcea_ Wm. Sm., 15 + _punctata_ Wm. Sm., 15 + _spinosa_ Grev., 15 + + _Paralia_ + _marina_ Heib., 15 + _sulcata_ (Ehr.) Cl., 15 + + Pinnularia, 101 + acrosphaeria (Breb.) Cl., 108 + var. turgidula Grun.?, 108 + aestuarii Cl., 105 + appendiculata (Ag.) Cl., 106 + blandita n. sp., 108 + borealis Ehr., 109 + var. scalaris (Ehr.) Cl., 109 + braunii Grun., 106 + brebissonii (Kuetz.) Cl., 107 + cardinaliculus Cl., 107 + _cyprinus_ Wm. Sm., 95 + dactylus Ehr., 103 + var. dariana (A. S.) Cl., 103 + var. demerarae Cl., 103 + divergens var. elliptica Grun., 107 + gentilis (Donk.) Cl., 103 + gibba (Kuetz.) V. H., 109 + _interrupta_ forma _stauroneiformis_ Cl., 106 + lata (Breb.) Wm. Sm., 109 + legumen Ehr., 107 + var.?, 107 + leptosoma Grun., 105 + major (Kuetz.) Wm. Sm., 102 + var. pulchella n. var., 102 + mesogongyla (Ehr.) Cl., 109 + mesolepta Ehr., 105 + var. stauroneiformis Grun., 105 + microstauron (Ehr.) Cl., 106 + molaris (Grun.) Cl., 105 + mormonorum Grun., 107 + nobilis Ehr., 103 + nodosa forma capitata Cl., 108 + parva (Ehr.) Cl., 108 + _permagna_ Bail., 82 + polyonca (Breb.) Lewis, 108 + rectangulata (Greg.) Cl., 110 + socialis (Palmer), 104 + stauroptera (Grun.) Cl., 110 + var. interrupta forma stauroneiformis Cl., 110 + stomatophora (Grun.) Cl., 109 + subcapitata Greg., 105 + var. paucistriata Grun., 106 + tabellaria (Ehr.) Cl., 110 + termes (Ehr.) A. S., 106 + var. stauroneiformis V. H., 106 + trigonocephala Cl., 103 + viridis Nitzsch, 104 + var. caudata n. var., 104 + var. fallax Cl., 104 + var.?, 104 + + Plagiogramma, 42 + obesum Grev., 43 + pygmaeum Grev., 43 + tessellatum Grev., 43 + wallichianum Grev., 43 + + Pleurosigma, 73 + aestuarii Breb., 74 + _affine_ var. _fossilis_ Grun., 74 + angulatum (Quekett) Cl., 74 + _balticum_ (Ehr.) Wm. Sm., 75 + formosum Wm. Sm., 73 + _hippocampus_ (Ehr.) Wm. Sm., 75 + naviculaceum Breb., 74 + _normanii_ var. _fossilis_ Grun., 74 + obscurum Wm. Sm., 74 + rigidum Wm. Sm., 75 + _simile_ Grun., 76 + _spencerii_ var. _acutiuscula_ Grun., 76 + var. _kuetzingii_ Grun., 76 + strigosum Wm. Sm., 74 + virginiacum H. L. S., 74 + + Podocystis, 128 + adriatica Kuetz., 129 + _americana_ Bail., 129 + + _Podosira_ + _hormoides_ Wm. Sm., 18 + _maculata_ Wm. Sm., 17 + + _Podosphenia_ + _baileyi_ (Edw.) Lewis, 40 + _ehrenbergii_ Kuetz., 40 + _lyngbyei_ Kuetz., 40 + + Polymyxus, 25 + coronalis L. W. Bail., 25 + + Pseudauliscus, 29 + radiatus (Bail.) Rattr., 29 + spinosus (Christian) Rattr., 29 + + Pyxidicula, 19 + _compressa_ Bail., 116 + var. _minor_ H. L. S., 116 + cruciata Ehr., 19 + _radiata_ O'Meara, 17 + + Rhabdonema, 35 + adriaticum Kuetz., 36 + arcuatum (Lyng.) Kuetz., 35 + minutum Kuetz., 36 + + Rhaphoneis, 46 + amphiceros Ehr., 46 + var. rhombica Grun., 46 + belgica var. intermedia Grun., 46 + + _Rhipidophora_ + _elongata_ Kuetz., 39 + _paradoxa_ Kuetz., 39 + + Rhoicosphenia, 56 + curvata (Kuetz.) Grun., 56 + + Rhopalodia, 112 + gibba (Kuetz.) Mueller, 112 + ventricosa (Kuetz.) Mueller, 113 + + _Schizonema_ + _cruciger_ Wm. Sm., 100 + _dillwynii_ Wm. Sm., 78 + _grevillei_ Ag., 99 + _smithii_ Kuetz., 95 + + _Scoliopleura_ + _tumida_ (Breb.) V. H., 99 + + Scoliotropis, 69 + latestriata var. amphora Cl., 69 + + Stauroneis, 88 + acuta Wm. Sm., 89 + americana A. S., 89 + anceps Ehr., 88 + var. amphicephala (Kuetz.) Cl., 88 + var. gracilis (Ehr.) Cl., 88 + crucicula (Grun.) Cl., 89 + _exilis_ Kuetz., 59 + frickei var. angusta n. var., 88 + legumen Ehr., 89 + _maculata_ Bail., 90 + phoenicenteron Ehr., 88 + salina Wm. Sm., 89 + smithii Grun., 89 + _spicula_ Hickie, 100 + + _Staurosira_ + _construens_ Ehr., 45 + + Stephanopyxis, 18 + _appendiculata_ Ehr., 18 + corona (Ehr.) Grun., 18 + turris (Grev.) Ralfs, 18 + + Striatella, 37 + interrupta (Ehr.) Heib., 38 + unipunctata (Lyng.) Ag., 38 + + Surirella, 124 + amphioxys Wm. Sm., 124 + anceps Lewis, 128 + angusta Kuetz., 127 + arctissima A. S., 128 + _bifrons_ Ehr., 124 + biseriata (Ehr.) Breb., 124 + _cardinalis_ Kitton, 126 + _circumsuta_ Bail., 118 + cruciata A. S., 127 + crumena Breb., 126 + _davidsonii_ A. S., 126 + delicatissima Lewis, 128 + _diaphana_ Bleisch, 125 + elegans Ehr., 125 + fastuosa Ehr., 127 + febigerii Lewis, 128 + gemma Ehr., 125 + gracilis Grun., 127 + guatimalensis Ehr., 126 + intermedia Lewis, 128 + linearis Wm. Sm., 124 + _moelleriana_ Grun., 124 + oblonga Ehr.?, 127 + ovalis Breb., 126 + var. _pinnata_ (Wm. Sm.) De Toni, 126 + panduriformis Wm. Sm., 126 + pinnata Wm. Sm., 126 + var. minuta Grun., 126 + recedens A. S., 127 + robusta Ehr., 124 + splendida (Ehr.) Kuetz., 125 + striatula Turpin, 125 + tenera Greg., 125 + + Synedra, 47 + acus Kuetz., 48 + affinis Kuetz., 50 + var. parva (Kuetz.) V. H., 50 + var. tabulata (Ag.) V. H., 50 + biceps (Kuetz.) A. S., 48 + capitata Ehr., 48 + danica Kuetz., 48 + fulgens (Grev.) Wm. Sm., 50 + goulardi Breb., 48 + _gracilis_ Kuetz., 50 + oxyrhynchus var. undulata Grun., 48 + pulchella (Ralfs) Kuetz., 48 + var. abnormis Macchiati?, 48 + var. flexella n. var., 49 + radians Kuetz., 49 + ulna (Nitzsch) Ehr., 47 + vaucheriae var. parvula (Kuetz.) Rab., 49 + + Tabellaria, 36 + fenestrata (Lyng.), 36 + flocculosa (Roth) Kuetz., 36 + + Terpsinoe, 34 + americana (Bail.) Ralfs, 34 + novae-caesareae Boyer, 34 + + _Tessella_ + _interrupta_ Ehr., 38 + + Trachyneis, 79 + aspera var. intermedia Grun., 79 + + Trachysphenia, 47 + australis Petit, 47 + + _Triceratium_ + _alternans_ Bail., 33 + _favus_ Ehr., 31 + _obtusum_ Br., 33 + _pileotus_ Ehr., 30 + _punctatum_ Br., 33 + _sculptum_ Shad., 33 + + Trinacria, 30 + pileolus (Ehr.) Grun., 30 + + _Tripodiscus_ + _argus_ Ehr., 26 + + Tropidoneis, 68 + lepidoptera (Greg.) Cl., 69 + + _Tryblionella_ + _punctata_ Wm. Sm., 116 + _scutellum_ Wm. Sm., 118 + + _Vibrio_ + _paxillifer_ O. F. Mueller, 119 + + + + +PLATES + + +PLATE 1 + + + + MELOSEIRA + + 3-4 Meloseira roeseana var. epidendron (Ehr.) Grun. 15 + + 5-6 Meloseira roeseana Rab. 15 + + 8-9 Meloseira distans (Ehr.) Kuetz. 14 + + 10 Meloseira granulata (Ehr.) Ralfs 15 + + 11-12 Meloseira sulcata Kuetz. 15 + + 15-16-17 Meloseira undulata (Ehr.) Kuetz. 15 + + GAILLONELLA + + 13-14 Gaillonella nummuloides (Dillw.) Bory 16 + + LYSIGONIUM + + 7 Lysigonium moniliforme (Muell.) Link. 16 + + 18-19 Lysigonium varians (Ag.) De Toni 17 + + HYALODISCUS + + 20 Hyalodiscus scoticus (Kuetz.) Grun. 18 + + 21 Hyalodiscus radiatus var. arctica Grun. 17 + + 22 Hyalodiscus stelliger Bail. 17 + + NOTE.--The figures in all of the plates, except when otherwise + noted, are magnified 800 diameters. + + + +[Illustration: PLATE 1] + + +PLATE 2 + + + + STEPHANOPYXIS + + 1-2 Stephanopyxis turris (Grev.) Ralfs 18 + + 3 Stephanopyxis corona (Ehr.) Grun. 18 + + CYCLOTELLA + + 4 Cyclotella meneghiniana var. stelligera Cl. and Grun. 20 + + 5-6 Cyclotella operculata (Ag.) Kuetz. 20 + + 7 Cyclotella comta (Ehr.) Kuetz. 20 + + 8 Cyclotella meneghiniana Kuetz. 19 + + 9 Cyclotella striata (Kuetz.) Grun. 19 + + 10 Cyclotella stylorum (Br.?) V. H. 20 + + 11 Cyclotella antiqua Wm. Sm. 20 + + 12 Cyclotella meneghiniana var. stellulifera Cl. and Grun. 20 + + COSCINODISCUS + + 13 Coscinodiscus denarius A. S. 22 + + 14 Coscinodiscus excentricus Ehr. 21 + + 15-17 Coscinodiscus subtilis Ehr. 21 + + 16 Coscinodiscus asteromphalus Ehr. 23 + + 18 Coscinodiscus nitidus Greg. 21 + + 19 Coscinodiscus nitidulus Grun. 21 + + 20 Coscinodiscus excentricus var. perpusilla Grun. ? 21 + + + +[Illustration: PLATE 2] + + +PLATE 3 + + + + COSCINODISCUS--Continued + + 1-11 Coscinodiscus radiatus Ehr. 23 + + 2 Coscinodiscus velatus Ehr. 22 + + 3 Coscinodiscus biangulatus A. S. 23 + + 4 Coscinodiscus subaulacodiscoidalis Rattr. 23 + + 5 Coscinodiscus lewisianus Grev. 24 + + 7 Coscinodiscus argus Ehr. 23 + + 8 Coscinodiscus lineatus Ehr. 21 + + 9 Coscinodiscus marginatus Ehr. 22 + + 10 Coscinodiscus oculus-iridis Ehr. 23 + + ACTINOCYCLUS + + 6 Actinocyclus ellipticus var. delawarensis n. var. 27 + + + +[Illustration: PLATE 3] + + +PLATE 4 + + + + ACTINOPTYCHUS + + 1-4-6 Actinoptychus undulatus (Kuetz.) Ralfs. 24 + + 2 Actinoptychus undulatus (inner stratum) 24 + + 3 Actinoptychus heliopelta Grun. var.? 25 + + 5 Actinoptychus vulgaris var. interrupta n. var. 24 + + POLYMYXUS + + 7 Polymyxus coronalis L. W. Bail. 25 + + AULACODISCUS + + 8 Aulacodiscus argus (Ehr.) A. S. 26 + + + +[Illustration: PLATE 4] + + +PLATE 5 + + + + EUODIA + + 1 Euodia gibba Bail. 34 + + POLYMYXUS + + 2 Polymyxus coronalis L. W. Bail., zone view 25 + + EUPODISCUS + + 3 Eupodiscus radiatus Bail. 28 + + AULISCUS + + 4 Auliscus caelatus Bail. 29 + + 5 Auliscus sculptus (Wm. Sm.) Ralfs 29 + + 6 Auliscus punctatus Bail. 28 + + 7 Auliscus (intermediate form between A. caelatus and A. + sculptus) 29 + + 8 Auliscus pruinosus Bail. 28 + + PSEUDAULISCUS + + 9 Pseudauliscus radiatus (Bail.) Rattr. 29 + + 10 Pseudauliscus spinosus (Christian) Rattr. 29 + + + +[Illustration: PLATE 5] + + +PLATE 6 + + + + ACTINOCYCLUS + + 1 Actinocyclus barkleyi var. aggregata Rattr. 27 + + 2 Actinocyclus moniliformis Ralfs. 27 + + BIDDULPHIA + + 3 Biddulphia antediluviana (Ehr.) V. H. 32 + + 5 Biddulphia reticulum (Ehr.) 33 + + 6 Biddulphia favus (Ehr.) V. H. 31 + + 7-8 Biddulphia alternans (Bail.) V. H. 33 + + TRINACRIA + + 9 Trinacria pileolus (Ehr.) Grun. 30 + + DITYLUM + + 4 Ditylum intricatum (West) Grun. 30 + + TERPSINOE + + 10 Terpsinoe americana (Bail.) Ralfs. 34 + + 11 Terpsinoe novae-caesareae Boyer 34 + + + +[Illustration: PLATE 6] + + +PLATE 7 + + + + BIDDULPHIA + + 1-2-3-4 Biddulphia biddulphiana (Smith) 31 + + 5 Biddulphia rhombus (Ehr.) Wm. Sm. 32 + + 6 Biddulphia granulata Roper 32 + + 7 Biddulphia turgida (Ehr.) Wm. Sm. 32 + + 8 Biddulphia smithii (Ralfs) V. H. 32 + + 9 Biddulphia laevis Ehr. 33 + + 10 Biddulphia laevis Ehr. Sporangial frustules (260 diam.) 33 + + EUNOTOGRAMMA + + 11 Eunotogramma laeve Grun. 33 + + + +[Illustration: PLATE 7] + + +PLATE 8 + + + + RHABDONEMA + + 1-2-3 Rhabdonema arcuatum (Lyng.) Kuetz. 35 + + 4-5-6 Rhabdonema adriaticum Kuetz. 36 + + 7 Rhabdonema minutum Kuetz. 36 + + TABELLARIA + + 8-9-10 Tabellaria flocculosa (Roth) Kuetz. 36 + + 11-12 Tabellaria fenestrata (Lyng.) Kuetz. 36 + + GRAMMATOPHORA + + 13-14 Grammatophora marina var. subtilissima (Bail.) V. H. 37 + + 15-16 Grammatophora angulosa var. hamulifera (Kuetz.) Grun. 37 + + 17-18 Grammatophora marina (Lyng.) Kuetz. 37 + + 19-20 Grammatophora islandica Ehr. 37 + + 21 Grammatophora serpentina Ralfs. 37 + + STRIATELLA + + 22-23 Striatella unipunctata (Lyng.) Ag. 38 + + 24 Striatella interrupta (Ehr.) Heib. 38 + + ATTHEYA + + 25 Attheya decora West 38 + + + +[Illustration: PLATE 8] + + +PLATE 9 + + + + LICMOPHORA + + 1-2 Licmophora flabellata (Carm.) Ag. 39 + + 3-4 Licmophora lyngbyei Kuetz. 40 + + 5 Licmophora ehrenbergii (Kuetz.) Grun. 40 + + 6-7 Licmophora paradoxa (Lyng.) Ag. 39 + + 8-9 Licmophora ovulum Mer. 39 + + 10 Licmophora baileyi (Edw.) Grun. 40 + + 11 Licmophora gracilis (Ehr.) Grun. 39 + + 12-13 Licmophora gracilis var. elongata (Kuetz.) De Toni 39 + + 14-15 Licmophora tincta (Ag.) Grun. 40 + + + +[Illustration: PLATE 9] + + +PLATE 10 + + + + MERIDION + + 1-2-3 Meridion circulare (Grev.) Ag. 40 + + DIATOMA + + 4 Diatoma vulgare var. grande (Wm. Sm.) Grun. 42 + + 5-6 Diatoma anceps (Ehr.) Kirchn. 42 + + 7-8 Diatoma hiemale (Lyng.) Heib. 42 + + 9-10 Diatoma vulgare Bory. 42 + + PLAGIOGRAMMA + + 11 Plagiogramma tessellatum Grev. 43 + + 12 Plagiogramma obesum Grev. 43 + + 13 Plagiogramma pygmaeum Grev. 43 + + 14 Plagiogramma wallichianum Grev. 43 + + EUNOTOGRAMMA + + 15 Eunotogramma laeve Grun. 33 + + OPEPHORA + + 16-19 Opephora schwartzii (Grun.) Petit. 43 + + 17 Opephora pinnata var. lanceolata n. var. 44 + + 18 Opephora pacifica (Grun.) Petit. 43 + + FRAGILARIA + + 20-21 Fragilaria virescens Ralfs. 44 + + 22-23 Fragilaria arctica Grun. 44 + + 24-25-27-28-29 Fragilaria undata Wm. Sm. 44 + + 26 Fragilaria undata Wm. Sm., var.? 44 + + 30 Fragilaria construens (Ehr.) Grun. 45 + + 31 Fragilaria harrisonii (Wm. Sm.) Grun. 45 + + 34 Fragilaria capucina var. mesolepta Rab. 45 + + 35 Fragilaria parasitica (Wm. Sm.) 45 + + 36 Fragilaria sp. ? 45 + + 37 Fragilaria linearis Cstr. 45 + + RHAPHONEIS + + 38 Rhaphoneis amphiceros Ehr. 46 + + 39-40 Rhaphoneis amphiceros var. rhombica Grun. 46 + + 41 Rhaphoneis belgica var. intermedia Grun. 46 + + SYNEDRA + + 32-33 Synedra radians Kuetz. 49 + + + +[Illustration: PLATE 10] + + +PLATE 11 + + + + SYNEDRA--Continued + + 1-5-6 Synedra ulna (Nitzsch) Ehr. Sporangial 47 + + 2 Synedra danica Kuetz. 48 + + 3 Synedra biceps (Kuetz.) A. S. 48 + + 4-7-11 Synedra ulna (Nitzsch) Ehr. 47 + + 8 Synedra capitata Ehr. 48 + + 9-18 Synedra acus Kuetz. 48 + + 10 Synedra fulgens (Grev.) Wm. Sm. 50 + + 12-13 Synedra goulardi Breb. 48 + + 14-15-16 Synedra pulchella (Ralfs) Kuetz. 48 + + 17 Synedra pulchella var. abnormis Macchiati? 48 + + + +[Illustration: PLATE 11] + + +PLATE 12 + + + + SYNEDRA--Continued + + 1 Synedra oxyrhynchus var. undulata Grun. 48 + + 2 Synedra pulchella var. flexella n. var. 49 + + 3 Synedra affinis Kuetz. 50 + + 4 Synedra affinis var. tabulata (Ag.) V. H. 50 + + 5-6 Synedra vaucheriae var. parvula (Kuetz.) Rab. 49 + + 7 Synedra affinis var. parva (Kuetz.) V. H. 50 + + 8 Synedra radians (Kuetz.) H. L. S. 49 + + DIMEROGRAMMA + + 9-10 Dimerogramma marinum (Greg.) 46 + + 11 Dimerogramma surirella (Ehr.) Grun. 46 + + 12-13-14 Dimerogramma minus (Greg.) Ralfs. 47 + + TRACHYSPHENIA + + 15 Trachysphenia australis Petit. 47 + + ACTINELLA + + 16-17-18 Actinella punctata Lewis. 54 + + ASTERIONELLA + + 19-20-21 Asterionella formosa Hass. 50 + + 22 Asterionella inflata Heib. 50 + + EUNOTIA + + 23 Eunotia hemicyclus (Ehr.) Ralfs 53 + + 24-25 Eunotia lunaris (Ehr.) Grun. 53 + + + +[Illustration: PLATE 12] + + +PLATE 13 + + + + EUNOTIA--Continued + + 1-2 Eunotia major (Wm. Sm.) Rab. 51 + + 3 Eunotia gracilis (Ehr.) Rab. 51 + + 4 Eunotia major (Wm. Sm.) Rab. (intermediate form) 51 + + 5 Eunotia praerupta Ehr. 53 + + 6-7 Eunotia pectinalis (Kuetz.) 52 + + 8-10 Eunotia pectinalis var. undulata Ralfs 52 + + 9 Eunotia pectinalis var. solierolii (Kuetz.) 52 + + 11 Eunotia luna Ehr. var.? 52 + + 12 Eunotia pectinalis var. ventricosa Grun. 52 + + 13 Eunotia robusta Ralfs (E. scalaris Ehr.) 53 + + 14 Eunotia robusta Ralfs (E. prioritis Ehr.) 53 + + 15 Eunotia robusta Ralfs (E. decadon Ehr.) 53 + + 16 Eunotia robusta Ralfs (E. octodon Ehr.) 53 + + 17-22 Eunotia robusta Ralfs (E. heptodon Ehr.) 53 + + 18 Eunotia bactriana Ehr. 54 + + 19 Eunotia praerupta var. bidens Grun. 53 + + 20 Eunotia bidentula Wm. Sm. 54 + + 21 Eunotia robusta Ralfs (E. diadema Ehr.) 53 + + 23 Eunotia praerupta Ehr. var.? 53 + + 24 Eunotia robusta Ralfs (E. triodon Ehr.) 53 + + 25 Eunotia robusta Ralfs (E. tetraodon Ehr.) 53 + + 26 Eunotia formica Ehr. var.? 54 + + 27 Eunotia biceps Ehr. 53 + + 28-29 Eunotia sp.? 54 + + 30-31 Eunotia veneris Kuetz. 52 + + 32 Eunotia nymanniana Grun. 51 + + + +[Illustration: PLATE 13] + + +PLATE 14 + + + + AMPHIPRORA + + 1-2 Amphiprora pulchra Bail. 68 + + 3 Amphiprora alata Kuetz. 68 + + 4 Amphiprora conspicua Grev. 68 + + 5 Amphiprora paludosa Wm. Sm. 68 + + 6-7 Amphiprora ornata Bail. 68 + + TROPIDONEIS + + 8-9 Tropidoneis lepidoptera (Greg.) Cleve. 69 + + SCOLIOTROPIS + + 10-11 Scoliotropis latestriata var. amphora Cleve. 69 + + + +[Illustration: PLATE 14] + + +PLATE 15 + + + + AMPHORA + + 1 Amphora robusta Greg. 65 + + 3 Amphora crassa Greg. 65 + + 4 Amphora obtusa Greg. 67 + + 5-6-19 Amphora proteus Greg. 65 + + 7 Amphora ovalis (Breb.) Kuetz. 65 + + 8-18 Amphora coffaeiformis (Ag.) Kuetz. 66 + + 9-10 Amphora lineolata Ehr. 66 + + 11 Amphora areolata Grun. 66 + + 12-21 Amphora ostrearia Breb. 66 + + 13 Amphora laevis Greg. 66 + + 14-15 Amphora ocellata var. cingulata Cleve. 67 + + 16 Amphora angusta var. culensteinii Grun. 67 + + 17 Amphora arenaria Donk. 67 + + 20 Amphora acuta Greg. 66 + + AURICULA + + 2 Auricula mucronata (H. L. Smith) Peragallo 69 + + + +[Illustration: PLATE 15] + + +PLATE 16 + + + + ACHNANTHES + + 1-2 Achnanthes longipes Ag. 58 + + 3 Achnanthes brevipes Ag. 59 + + 4-5-6 Achnanthes subsessilis Kuetz. 59 + + 7-8 Achnanthes inflata (Kuetz.) Grun. 59 + + 9 Achnanthes coarctata (Breb.) Grun. 59 + + 10-11-12 Achnanthes lanceolata (Breb.) Grun. 59 + + 13 Achnanthes danica (Floegel) Grun. (lower valve) 60 + + 14-15 Achnanthes exigua Grun. 59 + + 16-17 Achnanthes linearis forma curta H. L. Smith 59 + + COCCONEIS + + 18 Cocconeis scutellum var.? 57 + + 19-20 Cocconeis placentula Ehr. 57 + + 21 Cocconeis scutellum Ehr. (upper valve) 57 + + 22 Cocconeis dirupta Greg. (lower valve) 58 + + 23-24 Cocconeis pediculus Ehr. 57 + + 25-26 Cocconeis pellucida Grun. 58 + + 27-28 Cocconeis scutellum var. ornata Grun. 57 + + 29 Cocconeis placentula var. lineata (Ehr.) V. H. 58 + + ANORTHONEIS + + 30-31 Anorthoneis excentrica (Donk.) Grun. 56 + + + +[Illustration: PLATE 16] + + +PLATE 17 + + + + FRUSTULIA + + 1 Frustulia lewisiana (Grev.) De Toni 77 + + 2 Frustulia rhomboides (Ehr.) De Toni 77 + + 3 Frustulia rhomboides var. amphipleuroides Grun. 77 + + 4 Frustulia vulgaris (Thwaites) De Toni 77 + + 5 Frustulia interposita (Lewis) De Toni 78 + + 6 Frustulia rhomboides var. saxonica (Rab.) De Toni 77 + + BREBISSONIA + + 7 Brebissonia boeckii (Kuetz.) Grun. 79 + + 8 Brebissonia palmerii n. sp. 80 + + AMPHIPLEURA + + 9 Amphipleura pellucida Kuetz. 78 + + 10-11 Amphipleura rutilans (Trentepohl) Cl. 78 + + ANOMOEONEIS + + 12 Anomoeoneis serians (Breb.) Cl. 80 + + 13 Anomoeoneis serians forma minor 80 + + 14 Anomoeoneis follis (Ehr.) Cl. 80 + + TRACHYNEIS + + 15 Trachyneis aspera var. intermedia Grun. 70 + + MASTOGLOIA + + 16 Mastogloia kinsmanii Lewis 87 + + 17 Mastogloia angulata Lewis 87 + + 18 Mastogloia lanceolata Thwaites 87 + + 19 Mastogloia smithii Thwaites 87 + + 20 Mastogloia elegans Lewis 87 + + 21-22-23 Mastogloia apiculata Wm. Sm. 87 + + 24 Mastogloia exigua Lewis 87 + + + +[Illustration: PLATE 17] + + +PLATE 18 + + + + CYMBELLA + + 1 Cymbella aspera (Ehr.) Cl. 61 + + 2 Cymbella cymbiformis (Kuetz.) Breb. 62 + + 3 Cymbella cistula (Hempr.) Kirchn. 62 + + 4 Cymbella lanceolata (Ehr.) Kirchn. 62 + + 5 Cymbella mexicana (Ehr.) A. S. 62 + + 6 Cymbella naviculiformis Auerswald. 60 + + 7 Cymbella tumida (Breb.) V. H. 62 + + 8 Cymbella philadelphica n. sp. 63 + + 9 Cymbella ehrenbergii Kuetz. 60 + + 10 Cymbella heteropleura (Ehr.) Kuetz. 60 + + 11 Cymbella rhomboidea n. sp. 63 + + 12 Cymbella turgida (Greg.) Cl. var.? 63 + + 13 Cymbella sinuata Greg. 61 + + 14 Cymbella ventricosa Kuetz. 62 + + 15-19 Cymbella excisa (Kuetz.) De Toni. 61 + + 16 Cymbella amphicephala Naegeli. 61 + + 17 Cymbella cuspidata Kuetz. 60 + + 18 Cymbella affinis Kuetz. 61 + + 20 Cymbella gracilis (Rab.) Cl. 64 + + 21 Cymbella prostrata (Berk.) Cl. 63 + + 22 Cymbella ventricosa Kuetz.? 62 + + 23 Cymbella turgida (Greg.) Cl. 63 + + 24 Cymbella triangulum (Ehr.) Cl. 63 + + 25 Cymbella lacustris (Ag.) Cl. 64 + + + +[Illustration: PLATE 18] + + +PLATE 19 + + + + GOMPHONEIS + + 1 Gomphoneis mamilla (Ehr.) Cl. 70 + + 2 Gomphoneis herculaneum (Ehr.) Cl. 70 + + GOMPHONEMA + + 3 Gomphonema montanum Schum. 71 + + 4 Gomphonema geminatum Lyng. 71 + + 5 Gomphonema acuminatum var. turris (Ehr.) Cl. 71 + + 6-12 Gomphonema lanceolatum var. insignis (Greg.) Cl. 71 + + 7 Gomphonema acuminatum var. coronata (Ehr.) Cl. 71 + + 8 Gomphonema constrictum Ehr. 72 + + 9-10 Gomphonema sphaerophorum Ehr. 72 + + 11 Gomphonema acuminatum var. turris (Ehr.) Cl.? 71 + + 13 Gomphonema ventricosum Greg. 73 + + 14 Gomphonema intricatum Kuetz. 72 + + 15 Gomphonema aequale Greg. 72 + + 16 Gomphonema sarcophagus Greg. 72 + + 17 Gomphonema parvulum var. micropus (Kuetz.) Cl. 73 + + 18-19 Gomphonema angustatum Kuetz. 72 + + 20 Gomphonema acuminatum var. trigonocephala (Ehr.) Cl. 71 + + 21 Gomphonema augur Ehr. 72 + + 22 Gomphonema capitatum Ehr. 72 + + 23 Gomphonema olivaceum Lyng. 73 + + 24 Gomphonema brasiliense var. demerarae Grun.? 73 + + RHOICOSPHENIA + + 25-26-27 Rhoicosphenia curvata (Kuetz.) Grun. 56 + + + +[Illustration: PLATE 19] + + +PLATE 20 + + + + DICTYONEIS + + 1 Dictyoneis marginata var. maxima n. var. 79 + + 2 Dictyoneis marginata var. commutata Cleve. 79 + + 3 Dictyoneis marginata var. typica Cleve. 78 + + DIPLONEIS + + 4 Diploneis crabro var. pandura (Breb.) Cl. 85 + + 6 Diploneis campylodiscus (Grun.) Cl. 86 + + 7-8 Diploneis gruendleri (A. S.) Cl. 85 + + 9 Diploneis crabro Ehr. var.? 85 + + 10 Diploneis excentrica n. sp. 85 + + 11 Diploneis fusca var. delicata (A. S.) Cl. 85 + + 12 Diploneis puella (Schum.) Cl. 85 + + 13 Diploneis crabro var. pandurella Cl.? 85 + + 14 Diploneis elliptica (Kuetz.) Cl. 84 + + 15 Diploneis crabro var. expleta (A. S.) Cl. 85 + + 16 Diploneis geminata (Grev.) Cl. 86 + + 17 Diploneis smithii (Breb.) Cl. 84 + + NAVICULA + + 5 Navicula lyra Ehr. var.? 93 + + + +[Illustration: PLATE 20] + + +PLATE 21 + + + + CALONEIS + + 1 Caloneis permagna (Bail.) Cl. 82 + + 2 Caloneis permagna var. lewisiana n. var. 82 + + 3 Caloneis silicula (Ehr.) Cl. 81 + + 4 Caloneis silicula var. inflata (Grun.) Cl. 81 + + 5 Caloneis brevis var. vexans (Grun.) Cl. 82 + + 6-7 Caloneis wardii Cl. 82 + + 8 Caloneis trinodis (Lewis) 81 + + 9 Caloneis trinodis (Lewis) var.? 81 + + 10 Caloneis powellii (Lewis) Cl. 83 + + 18 Caloneis formosa (Greg.) Cl. 82 + + NEIDIUM + + 11 Neidium affine (Ehr.) Pfitzer 83 + + 12 Neidium affine var. genuina forma minor Cl. 83 + + 13 Neidium affine var. amphirhyncus (Ehr.) Cl. 83 + + 14 Neidium amphigomphus (Ehr.) Pfitzer. 83 + + 15 Neidium hitchcockii (Ehr.) Cl. 84 + + 16 Neidium productum (Wm. Sm.) Cl. 83 + + 17 Neidium iridus (Ehr.) Cl. 84 + + + +[Illustration: PLATE 21] + + +PLATE 22 + + + + PLEUROSIGMA + + 1 Pleurosigma strigosum Wm. Sm. 74 + + 2 Pleurosigma rigidum Wm. Sm. 75 + + 3 Pleurosigma angulatum (Quekett) Cl. 74 + + 4 Pleurosigma obscurum Wm. Sm. 74 + + 5 Pleurosigma formosum Wm. Sm. 73 + + 6 Pleurosigma naviculaceum Breb. 74 + + 7 Pleurosigma aestuarii Breb. 74 + + 8 Pleurosigma virginiacum H. L. Smith 74 + + + +[Illustration: PLATE 22] + + +PLATE 23 + + + + GYROSIGMA + + 1 Gyrosigma strigilis (Wm. Sm.) Cl. 76 + + 2 Gyrosigma balticum (Ehr.) Cl. 75 + + 3 Gyrosigma hippocampus (Ehr.) 75 + + 4 Gyrosigma simile (Grun.) 76 + + 5 Gyrosigma acuminatum (Kuetz.) Cl. 76 + + 6 Gyrosigma scalproides (Rab.) Cl. 76 + + 7 Gyrosigma parkeri var. stauroneioides Grun. 75 + + 8 Gyrosigma spencerii var. nodifera Grun. 76 + + 9 Gyrosigma fasciola (Ehr.) Cl. 77 + + + +[Illustration: PLATE 23] + + +PLATE 24 + + + + NAVICULA + + 1 Navicula maculata (Bail.) Cl. 90 + + 2 Navicula praetexta Ehr. 92 + + 3 Navicula latissima Greg. 90 + + 4 Navicula irrorata Grev. 93 + + 5 Navicula latissima var. elongata (Pant.) Cl. 91 + + 6 Navicula fuchsii Pant. 91 + + + +[Illustration: PLATE 24] + + +PLATE 25 + + + + NAVICULA + + 1 Navicula tumida (Breb.) Cl. 99 + + 2 Navicula brasiliensis var. bicuneata Cl. forma + constricta. 92 + + 3 Navicula delawarensis Grun. 92 + + 4-6 Navicula pusilla Wm. Sm. 91 + + 5 Navicula humerosa Breb. 91 + + 7 Navicula spectabilis var. emarginata Cl. 94 + + 8 Navicula pusilla var. subcapitata n. var. 91 + + 9 Navicula punctulata Wm. Sm. 92 + + 10 Navicula lyra Ehr. 93 + + 11 Navicula hennedyi var. manca A. S. 93 + + 12 Navicula hennedyi Wm. Sm. 93 + + 13 Navicula lyra var. dilatata A. S. 93 + + 14 Navicula yarrensis Grun. 101 + + 15 Navicula yarrensis Grun. (smaller form) 101 + + 16 Navicula yarrensis Grun. var.? 101 + + + +[Illustration: PLATE 25] + + +PLATE 26 + + + + NAVICULA + + 1-2 Navicula cuspidata Kuetz. 100 + + 3 Navicula cuspidata var. ambigua (Ehr.) Cl. 100 + + 4 Navicula spicula (Hickie) Cl. 100 + + 5 Navicula integra Wm. Sm. 99 + + 6 Navicula mutica Kuetz. 97 + + 8 Navicula americana Ehr. 98 + + 9 Navicula pupula var. bacillarioides Grun. 98 + + 10 Navicula bacillum Ehr. 98 + + 11 Navicula semen Ehr. 98 + + 12 Navicula atomus Naegeli. 100 + + 13 Navicula minima Grun. 98 + + 14 Navicula ramosissima (Ag.) Cl. 95 + + 15 Navicula crucigera (Wm. Sm.) Cl. 100 + + 16 Navicula viridula var. rostellata Kuetz. 95 + + 17 Navicula radiosa Kuetz. 94 + + 19 Navicula gracilis var. schizonemoides (Ehr.) V. H. 95 + + 20 Navicula peregrina Ehr. 94 + + 21 Navicula cyprinus (Wm. Sm.) 95 + + 22 Navicula reinhardtii Grun. 95 + + 23 Navicula lanceolata var. arenaria (Donk.) Cl. 95 + + 24 Navicula salinarum Grun. 95 + + 25 Navicula gastrum Ehr. 96 + + 26 Navicula anglica Ralfs. 96 + + DIPLONEIS + + 7 Diploneis oculata (Breb.) Cl. 86 + + STAURONEIS + + 18 Stauroneis frickei var. angusta n. var. 88 + + + +[Illustration: PLATE 26] + + +PLATE 27 + + + + STAURONEIS--Continued + + 1 Stauroneis phoenicenteron Ehr. 88 + + 2 Stauroneis acuta Wm. Sm. 89 + + 3 Stauroneis americana A. S. 89 + + 4 Stauroneis anceps var.? 88 + + 5 Stauroneis anceps var. gracilis (Ehr.) Cl. 88 + + 6 Stauroneis salina Wm. Sm. 89 + + 7 Stauroneis anceps var. amphicephala (Kuetz.) Cl. 88 + + 8 Stauroneis anceps var.? 88 + + 9 Stauroneis anceps var.? 88 + + 10 Stauroneis crucicula (Grun.) Cl. 89 + + 11 Stauroneis smithii Grun. 89 + + NAVICULA + + 12 Navicula lacustris Greg. 92 + + 13 Navicula hasta Pant. 97 + + 14 Navicula hasta var. punctata n. var. 97 + + 15 Navicula punctata var. asymmetrica Lagerstedt 92 + + 16 Navicula dicephala Wm. Sm. 96 + + 17 Navicula placenta Ehr. 94 + + 18-19 Navicula inflexa Greg. 96 + + 20 Navicula pinnata Pant.? 96 + + 21 Navicula oblonga Kuetz. 97 + + 22 Navicula pennata A. S. 96 + + 23 Navicula pygmaea Kuetz. 94 + + 24 Navicula humilis Donk. 96 + + + +[Illustration: PLATE 27] + + +PLATE 28 + + + + PINNULARIA + + 1 Pinnularia nobilis Ehr. 103 + + 2 Pinnularia major var. pulchella n. var. 102 + + 3 Pinnularia dactylus Ehr. 103 + + 4 Pinnularia major (Kuetz.) Wm. Sm. 102 + + + +[Illustration: PLATE 28] + + +PLATE 29 + + + + PINNULARIA--Continued + + 1 Pinnularia gentilis (Donk.) Cl. 103 + + 2 Pinnularia viridis Nitzsch. 104 + + 3 Pinnularia dactylus var. dariana (A. S.) Cl. 103 + + 4 Pinnularia viridis var. fallax Cl. 104 + + 5 Pinnularia socialis Palmer 104 + + 6 Pinnularia aestuarii Cl. 105 + + 7 Pinnularia rectangulata (Greg.) Cl. 110 + + 8 Pinnularia trigonocephala Cl. 103 + + 9 Pinnularia major (Kuetz.) Wm. Sm. (small form near P. + viridis) 102 + + 10 Pinnularia dactylus var. demerarae Cl. 103 + + 11 Pinnularia mormonorum (Grun.) 107 + + 12 Pinnularia brebissonii (Kuetz.) Cl. 107 + + 13 Pinnularia mesolepta Ehr. 105 + + 14 Pinnularia termes var. stauroneiformis V. H. 106 + + 15 Pinnularia molaris (Grun.) Cl. 105 + + 16 Pinnularia braunii Grun. 106 + + 17 Pinnularia termes (Ehr.) A. S. 106 + + 18 Pinnularia appendiculata (Ag.) Cl. 106 + + 19 Pinnularia microstauron (Ehr.) Cl. var.? 106 + + 20 Pinnularia subcapitata Greg. 105 + + + +[Illustration: PLATE 29] + + +PLATE 30 + + + + PINNULARIA--Continued + + 1 Pinnularia cardinaliculus Cl. 107 + + 2 Pinnularia viridis var. fallax Cl.? (var. B., Wm. + Sm.?). 104 + + 3 Pinnularia legumen Ehr. 107 + + 4 Pinnularia legumen var.? 107 + + 5 Pinnularia gibba (Kuetz.) V. H. 109 + + 6 Pinnularia mesogongyla (Ehr.) Cl. 109 + + 7 Pinnularia acrosphaeria (Breb.) Cl. 108 + + 8 Pinnularia acrosphaeria var. turgidula Grun. 108 + + 9 Pinnularia tabellaria (Ehr.) Cl. var.? 110 + + 10 Pinnularia leptosoma Grun. 105 + + 11 Pinnularia stauroptera var. interrupta Cl. 110 + + 12 Pinnularia stomatophora (Grun.) Cl. 109 + + 13 Pinnularia stauroptera (Grun.) Cl. 110 + + 14 Pinnularia parva (Ehr.) Cl. var.? 108 + + 15-19 Pinnularia nodosa forma capitata Cl. 108 + + 16 Pinnularia subcapitata var. paucistriata Grun. 105 + + 17 Pinnularia viridis Nitzsch var. 104 + + 18 Pinnularia viridis var. caudata n. var. 104 + + 20 Pinnularia mesolepta var. stauroneiformis Grun. 105 + + 21 Pinnularia polyonca (Breb.) Lewis. 108 + + 22 Pinnularia borealis Ehr. 109 + + 23 Pinnularia lata (Breb.) Wm. Sm. 109 + + 24 Pinnularia borealis var. scalaris (Ehr.) Cl. 109 + + 25 Pinnularia blandita n. sp. 108 + + + +[Illustration: PLATE 30] + + +PLATE 31 + + + + NAVICULA + + 1 Navicula elegans Wm. Sm. 101 + + 2 Navicula elegans var. cuspidata Cl. 101 + + 3-4 Navicula grevillei (Ag.) Cl. 99 + + 5 Navicula libellus Greg. 99 + + 6-7 Navicula palpebralis Breb. 101 + + 8 Navicula rhyncocephala Kuetz. 97 + + 9 Navicula cryptocephala Kuetz. 97 + + 10 Navicula longa (Greg.) Ralfs. 97 + + PINNULARIA + + 11 Pinnularia brebissonii (Kuetz.) Cl. 107 + + 12 Pinnularia borealis Ehr. 109 + + 13 Pinnularia divergens var. elliptica Grun. 107 + + EPITHEMIA + + 14 Epithemia turgida (Ehr.) Kuetz. 111 + + 15-21 Epithemia argus Kuetz. 111 + + 16 Epithemia argus var.? 111 + + 17 Epithemia muelleri A. S. 111 + + 18 Epithemia zebra var. proboscidea (Kuetz.) Grun. 112 + + 19 Epithemia gibberula var. producta Grun. 112 + + 20 Epithemia musculus Kuetz. 112 + + 22 Epithemia musculus var. constricta (Breb.) V. H. 112 + + RHOPALODIA + + 23 Rhopalodia gibba (Kuetz.) Mueller 112 + + 24 Rhopalodia ventricosa (Kuetz.) Mueller 113 + + + +[Illustration: PLATE 31] + + +PLATE 32 + + + + NITZSCHIA + + 1 Nitzschia circumsuta (Bail.) Grun. 118 + + 2 Nitzschia plana Wm. Sm. 117 + + 3 Nitzschia granulata Grun. 116 + + 4 Nitzschia navicularis (Breb.) Grun. 116 + + 5 Nitzschia panduriformis var. minor Grun. 117 + + 6 Nitzschia apiculata (Greg.) Grun. 117 + + 7 Nitzschia tabellaria Grun. 119 + + 8 Nitzschia tryblionella Hantzsch 116 + + 10-11 Nitzschia bilobata Wm. Sm. 118 + + 12 Nitzschia litoralis var. delawarensis Grun. 118 + + 13 Nitzschia acuminata (Wm. Sm.) Grun. 117 + + 14-25 Nitzschia amphibia Grun. 122 + + 15 Nitzschia palea (Kuetz.) Wm. Sm. 122 + + 16 Nitzschia fluminensis Grun. 120 + + 17 Nitzschia obtusa var. scalpelliformis Grun. 121 + + 18 Nitzschia linearis (Ag.) Wm. Sm. 122 + + 19 Nitzschia communis Rab. 122 + + 20 Nitzschia clausii Hantzsch. 121 + + 21 Nitzschia epithemioides Grun. 118 + + 24 Nitzschia vermicularis (Kuetz.) Wm. Sm. 120 + + HANTZSCHIA + + 9 Hantzschia amphioxys (Ehr.) Grun. 113 + + 22 Hantzschia marina (Donk.) Grun. 114 + + 23 Hantzschia virgata (Roper) Grun. 114 + + + +[Illustration: PLATE 32] + + +PLATE 33 + + + + NITZSCHIA + + 1 Nitzschia longissima (Breb.) Ralfs 123 + + 2 Nitzschia intermedia Hantzsch 122 + + 3 Nitzschia spectabilis var. americana Grun. 122 + + 4-5 Nitzschia sigmatella Greg. 121 + + 6 Nitzschia scalaris (Ehr.) Wm. Sm. 119 + + 7 Nitzschia macilenta Greg. 120 + + 8 Nitzschia insignis Greg. 119 + + 9 Nitzschia vermicularis (Kuetz.) Hantzsch 120 + + 10 Nitzschia longissima forma parva V. H. 123 + + 11 Nitzschia reversa Wm. Sm. 123 + + 12 Nitzschia acicularis (Kuetz.) Wm. Sm. 123 + + 13-14 Nitzschia paxillifer (O. F. Mueller) Heib. 119 + + HOMOEOCLADIA + + 15 Homoeocladia filiformis Wm. Sm. 123 + + + +[Illustration: PLATE 33] + + +PLATE 34 + + + + SURIRELLA + + 1 Surirella striatula Turpin 125 + + 2 Surirella anceps Lewis 128 + + 3 Surirella intermedia Lewis 128 + + 4 Surirella arctissima A. S. 128 + + 5-6 Surirella delicatissima Lewis 128 + + 7 Surirella intermedia Lewis forma minor? 128 + + CYMATOPLEURA + + 8-9 Cymatopleura solea (Breb.) Wm. Sm. 129 + + + +[Illustration: PLATE 34] + + +PLATE 35 + + + + SURIRELLA + + 1 Surirella fastuosa Ehr. 127 + + 2 Surirella biseriata (Ehr.) Breb. 124 + + 3 Surirella splendida (Ehr.) Kuetz. 125 + + 4 Surirella crumena Breb. 126 + + 5 Surirella ovalis Breb. 126 + + 6 Surirella tenera Greg. 125 + + 7 Surirella recedens A. S. 127 + + 8 Surirella linearis Wm. Sm. 124 + + 9 Surirella oblonga Ehr.? 127 + + 10 Surirella cruciata A. S. 127 + + 11 Surirella gracilis Grun. 127 + + 12-13 Surirella amphioxys Wm. Sm. 124 + + + +[Illustration: PLATE 35] + + +PLATE 36 + + + + SURIRELLA--Continued + + 1 Surirella elegans Ehr. 125 + + 2 Surirella robusta Ehr. 124 + + 3 Surirella febigerii Lewis 128 + + 4 Surirella gemma Ehr. 125 + + 5 Surirella guatimalensis Ehr. 126 + + 6 Surirella panduriformis Wm. Sm. 126 + + 7-9 Surirella pinnata Wm. Sm. 126 + + 8 Surirella angusta Kuetz. 127 + + + +[Illustration: PLATE 36] + + +PLATE 37 + + + + CYMATOPLEURA + + 1 Cymatopleura elliptica (Breb.) Wm. Sm. 129 + + 2 Cymatopleura elliptica forma spiralis 129 + + 3-4 Cymatopleura marina Lewis 129 + + CAMPYLODISCUS + + 5 Campylodiscus hibernicus Ehr. 130 + + 6 Campylodiscus echeneis Ehr. 130 + + + +[Illustration: PLATE 37] + + +PLATE 38 + + + + 1 Amphora gigantea var. fusca A. S. 65 + + 2 Meloseira crenulata (Ehr.) Kuetz. 15 + + 3-4 Licmophora baileyi (Edw.) Grun. 40 + + 5 Coscinodiscus polyacanthus Grun. 22 + + 6-7 Ditylum intricatum (West) Grun. 30 + + 8 Pyxidicula cruciata Ehr. 19 + + 9 Gyrosigma scalproides (Rab.) Cl. 76 + + 10 Coscinodiscus asteromphalus var. omphalantha (Ehr.) + Grun. 23 + + 11 Rhabdonema minutum Kuetz. 36 + + 12 Gyrosigma kuetzingii (Grun.) Cl. 76 + + 13 Gyrosigma prolongatum (Wm. Sm.) Cl. 76 + + 14 Cymbella parva (Wm. Sm.) Cl. 61 + + 15 Gomphoneis herculaneum (Ehr.) Cl. (zone view) 70 + + 16 Cymbella ventricosa Kuetz. 62 + + 17-18 Eunotia sp. (abnormal?) 54 + + + +[Illustration: PLATE 38] + + +PLATE 39 + + + + 1 Nitzschia spectabilis var. americana Grun. (zone view) 122 + + 2 Nitzschia panduriformis Greg. 117 + + 3 Hantzschia amphioxys (Ehr.) Grun. 113 + + 4 Hantzschia amphioxys var. major Grun. 114 + + 5 Nitzschia dubia Wm. Sm. 118 + + 6 Nitzschia amphioxys Wm. Sm. 114 + + 7 Nitzschia compressa (Bail.) 116 + + 8 Nitzschia compressa var. minor H. L. Smith 116 + + 9 Surirella intermedia Lewis (zone view) 128 + + 10 Surirella arctissima A. S. forma minor 128 + + 11 Surirella ovalis Breb. 126 + + 12 Surirella biseriata (Ehr.) Breb. 124 + + 13 Nitzschia sigma (Kuetz.) Wm. Sm. 121 + + 14 Nitzschia obtusa var. flexella H. L. Smith 121 + + 15 Stauroneis legumen Ehr. 89 + + 16 Nitzschia obtusa Wm. Sm. 121 + + + +[Illustration: PLATE 39] + + +PLATE 40 + + + + 1 Caloneis liber (Wm. Sm.) Cl. 81 + + 2 Anomoeoneis sphaerophora (Kuetz.) Cl. 80 + + 3 Nitzschia spathulata Breb. 120 + + 4 Stauroneis ? abnormal 89 + + 5 Navicula ? abnormal 101 + + 6 Podocystis adriatica Kuetz. 129 + + 7 Nitzschia dissipata (Kuetz.) Grun. 120 + + 8 Cymbella ventricosa Kuetz. (zone view) 62 + + 9 Navicula radiosa Kuetz. (zone view) 94 + + 10 Detail of Rhabdonema arcuatum (Lyng.) Kuetz. 35 + + 11 Diatoma anceps (Ehr.) Kirchn. (containing + chromataphores) 42 + + 12 Coscinodiscus asteromphalus Ehr. (trans. section, after + Pelletan) 23 + + 13-14-15 Transverse section (diagram) of Pinnularia showing + straight, oblique and grooved raphes 101 + + 16 Transverse section (diagram) of Biddulphia favus + showing inner punctate stratum (after Deby) 31 + + 17 Transverse (ideal) section of Surirella 124 + + 18-19 Transverse (ideal) section of Pinnularia, before and + after division 101 + + 20 Transverse section of Nitzschia linearis (Ag.) Wm. Sm. 122 + + 21 Transverse section (diagram) of Navicula 89 + + 22 Transverse section (diagram) of Cymbella 60 + + 23 Transverse section (diagram) of Amphora 65 + + + +[Illustration: PLATE 40] + + + + + +End of the Project Gutenberg EBook of The Diatomaceae of Philadelphia and +Vicinity, by Charles Sumner Boyer + +*** END OF THIS PROJECT GUTENBERG EBOOK DIATOMACEAE *** + +***** This file should be named 44569.txt or 44569.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/4/4/5/6/44569/ + +Produced by Charlene Taylor, Bryan Ness, Keith Edkins and +the Online Distributed Proofreading Team at +http://www.pgdp.net (This file was produced from images +generously made available by The Internet Archive) + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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