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+The Project Gutenberg EBook of Jaw Musculature of the Mourning and
+White-winged Doves, by Robert L. Merz
+
+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: Jaw Musculature of the Mourning and White-winged Doves
+
+Author: Robert L. Merz
+
+Release Date: April 17, 2010 [EBook #32018]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK JAW MUSCULATURE--DOVES ***
+
+
+
+
+Produced by Chris Curnow, Joseph Cooper, Diane Monico, and
+the Online Distributed Proofreading Team at
+https://www.pgdp.net
+
+
+
+
+
+
+
+
+
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS
+MUSEUM OF NATURAL HISTORY
+
+Volume 12, No. 12, pp. 521-551, 22 figs.
+October 25, 1963
+
+
+Jaw Musculature
+Of the Mourning and White-winged Doves
+
+
+BY
+
+ROBERT L. MERZ
+
+
+UNIVERSITY OF KANSAS
+LAWRENCE
+1963
+
+
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY
+
+Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
+Theodore H. Eaton, Jr.
+
+Volume 12, No. 12, pp. 521-551, 22 figs.
+Published October 25, 1963
+
+
+UNIVERSITY OF KANSAS
+Lawrence, Kansas
+
+
+PRINTED BY
+JEAN M. NEIBARGER, STATE PRINTER
+TOPEKA, KANSAS
+1963
+
+29-7865
+
+
+
+
+Jaw Musculature
+Of the Mourning and White-winged Doves
+
+BY
+
+ROBERT L. MERZ
+
+
+For some time many investigators have thought that the genus _Zenaida_,
+which includes the White-winged and Zenaida doves, and the genus
+_Zenaidura_, which includes the Mourning, Eared, and Socorro doves
+(Peters, 1937:83-88), are closely related, perhaps more closely than is
+indicated by separating the several species into two genera. It is the
+purpose of this paper to report investigations on the musculature of
+the jaw of doves with the hope that, together with the results of other
+studies, the relationships of the genera _Zenaida_ and _Zenaidura_ can
+be elucidated.
+
+
+METHODS AND MATERIALS
+
+In order to determine in each species the normal pattern of musculature
+of the jaws, heads of 13 specimens of doves were dissected (all
+material is in the Museum of Natural History of The University of
+Kansas): White-winged Doves (_Zenaida asiatica_), 40323, 40324, 40328,
+40392, 40393; Zenaida Doves (_Z. aurita_), 40399, 40400; Mourning Doves
+(_Zenaidura macroura_), 40326, 40394, 40395, 40396, 40397, 40398.
+
+Thirty-seven skulls from the collection of the Museum of Natural
+History of The University of Kansas and two skulls from the United
+States National Museum were measured. The measurements are on file in
+the Library of The University of Kansas in a dissertation deposited
+there by me in 1963 in partial fulfillment of requirements for the
+degree of Master of Arts in Zoology. Specimens used were: White-winged
+Doves, KU 19141, 19142, 19143, 19144, 19145, 19146, 19147, 23138,
+23139, 24337, 24339, 24341, 23592, 23593, 24340, 31025, 31276; Mourning
+Doves, KU 14018, 14781, 15347, 15533, 15547, 15550, 15662, 15778,
+15872, 16466, 17782, 17786, 17788, 17795, 19153, 19242, 20321, 21669,
+22394, 22715; Eared Doves (_Zenaidura auriculata_), USNM 227496,
+318381. Additionally, the skulls of the Zenaida Doves mentioned above
+were measured. All measurements were made with a dial caliper and read
+to tenths of a millimeter.
+
+
+ACKNOWLEDGMENTS
+
+My appreciation is extended to Professor Richard F. Johnston, who
+advised me during the course of this study, and to Professors A. Byron
+Leonard and Theodore H. Eaton for critically reading the manuscript.
+
+I would like also to acknowledge the assistance of Dr. Robert M. Mengel
+and Mr. Jon C. Barlow for suggestions on procedure, and Mr. William C.
+Stanley, who contributed specimens of Mourning Doves for study. Mr.
+Thomas H. Swearingen offered considerable advice on production of
+drawings and Professor E. Raymond Hall suggested the proper layout of
+the same and gave editorial assistance otherwise, as also did Professor
+Johnston.
+
+
+MYOLOGY
+
+The jaw musculature of doves is not an imposing system. The eating
+habits impose no considerable stress on the muscles; the mandibles are
+not used for crushing seeds, spearing, drilling, gaping, or probing as
+are the mandibles of many other kinds of birds. Doves use their
+mandibles to procure loose seeds and grains, which constitute the major
+part of their diet (Leopold, 1943; Kiel and Harris, 1956: 377; Knappen,
+1938; Jackson, 1941), and to gather twigs for construction of nests.
+Both activities require but limited gripping action of mandibles. The
+crushing habit of a bird such as the Hawfinch (_Coccothraustes
+coccothraustes_), on the other hand, involves extremely powerful
+gripping (see, for example, Sims, 1955); the contrast is apparent in
+the development of the jaw musculature in the two types. Consequently,
+it is not surprising to find a relatively weak muscle mass in the jaw
+of doves, and because the musculature is weak there are few pronounced
+osseous fossae, cristae and tubercles. As a result, the bones, in
+addition to being small in absolute size, are relatively weaker when
+compared to skulls of birds having more distinctive feeding habits
+which require more powerful musculature.
+
+The jaw muscles of the species dissected for this study are, in gross
+form, nearly identical from one species to another. Thus, a description
+of the pertinent myology of each species is unnecessary; one basic
+description is hereby furnished, with remarks on the variability
+observed between the species.
+
+The terminology adopted by me for the jaw musculature is in boldfaced
+italic type. Synonyms are in italic type and are the names most often
+used by several other writers.
+
+ ~_M. pterygoideus ventralis:_~ part of Mm. pterygoidei, Gadow,
+ 1891:323-325, table 26, figs. 1, 2, 3 and 4, and table 27,
+ fig. 3--part of M. pterygoideus internus, Shufeldt, 1890:20,
+ figs. 3, 5, 6, 7 and 11--part of M. adductor mandibulae
+ internus, Edgeworth, 1935:58, figs. 605c and 607--part of M.
+ pterygoideus anterior, Adams, 1919:101, pl. 8, figs. 2 and 3.
+
+ ~_M. pterygoideus dorsalis:_~ part of Mm. pterygoidei,
+ Gadow, 1891:323-325, table 26, fig. 7 and table 27, figs. 1
+ and 3--part of M. pterygoideus internus, Shufeldt,
+ 1890:20--part of M. adductor mandibulae internus, Edgeworth,
+ 1935:58, fig. 605c--? part of M. pterygoideus anterior,
+ Adams, 1919:101, pl. 8, figs. 2 and 3.
+
+ ~_M. adductor mandibulae externus:_~ _a_) ~_pars
+ superficialis:_~ parts 1 and 2 of M. temporalis, Gadow,
+ 1891:320-321--part of M. temporal, Shufeldt, 1890:16,
+ figs. 5 and 7--part of M. adductor mandibulae externus,
+ Edgeworth, 1935:58-60--M. capiti-mandibularis medius and
+ profundus, Adams, 1919:101, pl. 8, fig. 1.
+
+ _b_) ~_pars medialis:_~ ? parts 1, 2 and 3 of M. temporalis,
+ Gadow, 1891:320-322--part of M. masseter and ? part of M.
+ temporal, Shufeldt, 1890:16-18, figs. 5, 6, 7 and 11--part
+ of M. adductor mandibulae externus, Edgeworth,
+ 1935:58-60--M. capiti-mandibularis superficialis, first
+ part, Adams, 1919:100-101, pl. 8, fig. 1.
+
+ _c_) ~_pars profundus:_~ part 2 of M. temporalis, Gadow,
+ 1891:321, table 27, fig. 2--part of M. temporal and ? part
+ of M. masseter, Shufeldt, 1890:16-18--part of M. adductor
+ mandibulae externus, Edgeworth, 1935:58-60--? part of M.
+ capiti-mandibularis medius and all of pars superficialis,
+ second part, Adams, 1919:100-101.
+
+ ~_M. pseudotemporalis profundus:_~ M. quadrato-maxillaris,
+ Gadow, 1891:322-323--M. pterygoideus externus, Shufeldt,
+ 1890:20-21, figs. 3, 5 and 11--part of M. adductor mandibulae
+ medius, Edgeworth, 1935:58-59--? part of M. pterygoideus
+ posterior, Adams, 1919:101, pl. 8, figs. 2 and 3.
+
+ ~_M. protractor pterygoidei:_~ part 4b of M. temporalis,
+ Gadow, 1891: 322-323, table 27, fig. 4--part of M.
+ entotympanious, Shufeldt, 1890:19-20, figs. 3 and 11--part
+ of M. spheno-pterygo-quadratus, Edgeworth, 1935:57.
+
+ ~_M. depressor mandibulae:_~ M. digastricus s. depressor
+ mandibulae, Gadow, 1891:318-319--M. biventer maxillae,
+ Shufeldt, 1890:18-19, figs. 3, 4, 5, 6, 7 and 11.
+
+ ~_M. pseudotemporalis superficialis:_~ M. spheno-maxillaris,
+ Gadow, 1891:323--part of M. temporal, Shufeldt, 1890:16--part
+ of M. pseudotemporalis, Hofer, 1950:468-477--part of M.
+ adductor mandibulae medius, Edgeworth, 1935:277.
+
+ ~_M. adductor mandibulae posterior:_~ ? part of M. temporal,
+ Shufeldt, 1890:16--part of M. adductor mandibulae medius,
+ Edgeworth, 1935:58-59--? part of M. pterygoideus posterior,
+ Adams, 1919:101, pl. 8, figs. 2 and 3.
+
+ ~_M. protractor quadrati:_~ part 4a of M. temporalis, Gadow,
+ 1891:322-323, table 27, fig. 4--part of M. entotympanicus,
+ Shufeldt, 1890:19-20, figs. 3 and 11--part of M.
+ spheno-pterygo-quadratus, Edgeworth, 1935:57.
+
+The terminology adopted by me is that of Lakjar (1926) except that the
+divisions of _M. depressor mandibulae_ are designated by the Latinized
+equivalents of the names used by Rooth (1953:261-262).
+
+~_M. pterygoideus ventralis lateralis._~--The origin is fleshy and by
+aponeurosis on the ventral side of the palatine anterior to the
+palatine fossa. The insertion is fleshy on the ventromedial surface of
+the lower mandible and continues along the anteromedial surface of the
+internal angular process to its distal tip. A few fibers leave _pars
+lateralis_ and insert on an aponeurosis which receives also all the
+fibers of _M. pterygoideus dorsalis lateralis_. The latter fact may
+have prompted Rooth (1953:257) to make the statement that the fibers
+originating on the dorsal part of the palatine inserted more laterally
+than those originating on the ventral side. Rooth worked with _Columba
+palumbus_, the Woodpigeon, and his description concerned _M. adductor
+mandibulae internus pterygoideus_, which is composed of _Mm.
+pterygoideus ventralis et dorsalis_ of Lakjar (1926). His assertion
+that ventral fibers, that is to say, fibers arising on the ventral
+surface of the palatine, insert medially does not appear to be
+completely true for doves.
+
+Aponeuroses cover most of the lower surface of the muscle and one or
+two nerves extend into the substance of the muscle. The nerves run from
+the anterior edge of _M. pterygoideus dorsalis medialis_ and farther
+posteriorly from a separation in the muscle.
+
+~_M. pterygoideus ventralis medialis._~--The origin is by aponeurosis
+from the ventral surface of the palatine and fleshy from the palatine
+fossa. The aponeurosis is the same that gives origin to the fibers of
+_pars lateralis_. Part of the aponeurosis becomes tendonlike in the
+middle of _M. pterygoideus ventralis_ and separates its two divisions.
+The insertion is fleshy on the lower one-third of the anterior surface
+of the internal angular process of the lower mandible, and by two
+tendons on the distal tip of that process. Many of the fibers of _pars
+medialis_ insert on the tendons. The fibers at their insertion are not
+distinctly separate from those of _pars lateralis_ and there is
+considerable mingling of the fibers. Consequently, the medial part of
+_M. pterygoideus ventralis_ cannot be removed as a part distinct from
+the lateral part (figs. 1, 4, 10, 21 and 22).
+
+Ordinarily _M. pterygoideus ventralis_ does not cross the ventral edge
+of the lower mandible, but in one white-wing the muscle was slightly
+expanded on the right side and it could be seen in lateral view. The
+homologous muscle in _Columba palumbus_ apparently is consistently
+visible in lateral view. (See Rooth, 1953, fig. 6.)
+
+~_M. pterygoideus dorsalis medialis._~--The origin is fleshy on the
+dorsolateral surface of the palatine immediately anterior to the
+pterygoid and also on the anterior, dorsolateral, posterior and
+ventromedial surfaces of the pterygoid. The insertion is fleshy on the
+ventromedial surface of the lower mandible and the anterior surface of
+the internal angular process immediately dorsal to the insertion of _M.
+pterygoideus ventralis lateralis_.
+
+~_M. pterygoideus dorsalis lateralis._~--The origin is fleshy from the
+dorsolateral surface of the palatine, anterior to the origin of _pars
+medialis_ and the insertion is by means of an aponeurosis on the medial
+surface of the lower mandible, lateral to the insertion of _M.
+pterygoideus ventralis lateralis_. The aponeurosis crosses the medial
+side of the insertion of _M. pterygoideus dorsalis medialis_. The
+fibers run in a posteroventrolateral direction and insert on the
+ventromedial side of the aponeurosis (figs. 1, 6, 8, 9, 13-22).
+
+In one individual, a Mourning Dove, the origin of _pars lateralis_ of
+_M. pterygoideus dorsalis_ extended to the pterygoid. With this one
+exception the muscle was uniform throughout the several species.
+
+~_M. adductor mandibulae externus._~--This is the most complex muscle
+in the jaw owing to its system of tendons and aponeuroses. Three
+divisions of this muscle were described by Lakjar (1926:45-46) and the
+divisions appear to be distinguishable in the doves, but there is no
+clear line of demarcation for any of the parts and the following
+description is based upon my own attempts to delineate the muscle.
+
+~_M. adductor mandibulae externus superficialis._~--The origin is
+fleshy from the most lateral area of the temporal fossa. Dorsally the
+origin is bounded by the base of the postorbital process and ventrally
+by the temporal process. The fibers converge upon a tendon that passes
+beneath the postorbital ligament and runs anteriorly among the fibers
+of _pars profundus_. The insertion is tendinous on the dorsal surface
+of the lower mandible in common with the dorsal aponeurosis of _pars
+profundus_. The insertion is immediately anterior to the ventral
+aponeurosis of _pars profundus_ near the medial edge of the dorsal
+surface on a tubercle at the posterior end of the dorsal ridge of the
+lower mandible.
+
+~_M. adductor mandibulae externus medialis._~--The origin is by a flat,
+heavy tendon from the temporal process. The tendon is attached almost
+vertically on the temporal process. It twists approximately 130° as it
+runs anteriorly, and becomes a thin aponeurosis, which gives rise on
+its dorsal and ventral surfaces to many fibers that insert in a
+fan-shaped area on the mandibular fossa. Fibers from the dorsal and
+dorsomedial sides of the heavy tendon run rostrad and insert on the
+ventral surface of the dorsal aponeurosis of _pars profundus_. From the
+ventral surface the most posterior fibers converge on an aponeurosis
+that inserts on a transverse crista on the dorsal surface of the
+mandible immediately lateral to the ventral aponeurosis of _pars
+profundus_ and dorsal to the insertion of ~_M. adductor mandibulae
+posterior_~. The more anterior fibers insert fleshily on the mandibular
+fossa. The tendon of origin is actually one with the ventral
+aponeurosis of _pars profundus_, which is situated in a horizontal
+plane. The insertion is primarily a fleshy attachment on the mandibular
+fossa. Some of the fibers that arise on the dorsomedial and lateral
+surfaces of the tendon of origin attach to another tendon, which
+inserts in the midline of the mandibular fossa on a small tubercle near
+the anterior end. Also, there is insertion by an aponeurosis anterior
+to _M. adductor mandibular posterior_ as stated above. Fibers attach to
+the dorsal and ventral side of the aponeurosis.
+
+~_M. adductor mandibulae externus profundus._~--The origin is fleshy
+from the medial surface of the temporal fossa, the posterior wall of
+the orbit and the otic process of the quadrate. The origin is bounded
+laterally by the origin of _pars superficialis_ and medially by the
+origin of _M. pseudotemporalis superficialis_. Ventrally the muscle
+lies against its own ventral aponeurosis, which originates on the
+posterior wall of the orbit immediately above the articulation of the
+otic process of the quadrate, and which also receives many fibers from
+the surface of the quadrate. The insertion is primarily by means of two
+aponeuroses. The most dorsal aponeurosis inserts on a tubercle at the
+posterior tip of the dorsal edge of the mandible. The lateral tendon of
+_M. pseudotemporalis superficialis_ converges with the aponeurosis. It
+is superficial and there are no fibers on its dorsal surface. The
+ventral aponeurosis inserts on a crista immediately below the insertion
+of the dorsal aponeurosis. It receives fibers on its ventral surface
+from the otic process of the quadrate, and on its dorsal surface gives
+rise to fibers that insert on the dorsal aponeurosis (figs. 2, 3, 5, 9,
+10, 11, 13-18).
+
+The tendon of insertion of _pars medialis_ of _M. adductor mandibulae
+externus_ does not become a superficial aponeurosis posteriorly in the
+Zenaida Dove as it does in the Mourning and White-winged doves.
+
+~_M. pseudotemporalis profundus._~--The origin is fleshy from the
+medial and partially from the dorsal surface of the lower mandible. The
+origin is almost completely anterior to and partly dorsal and ventral
+to the medial (most anterior) insertion of _M. pseudotemporalis
+superficialis_. The anterior margin of the origin is at the point where
+the mandibular ramus of the trigeminal nerve enters the mandible.
+Posteriorly the origin is bounded by the insertion of _M. adductor
+mandibulae posterior_, and ventrally by a ridge that is situated about
+halfway down the medial side of the mandible. The insertion is by
+aponeurosis on the tip of the orbital process of the quadrate and
+fleshily on the anterior surface of the same process. The aponeurosis
+extends about three-fifths of the distance along the muscle and it is
+dorsal or superficial to all of the fibers. Many fibers insert on the
+ventral side of the aponeurosis (figs. 1, 5, 13, 14, 15, 16, 21 and
+22).
+
+This muscle is the most variable of all the jaw muscles. In the
+Mourning Dove the muscle appears rather slender in dorsal view and in
+the White-winged Dove has an enlarged lateral belly that gives the
+appearance of a thicker muscle. In the Zenaida Dove _M.
+pseudotemporalis profundus_ is intermediate in shape between those of
+the other two species. This muscle will be discussed in detail later.
+
+~_M. protractor pterygoidei._~--The origin is fleshy from the junction
+of the sphenoidal rostrum and the interorbital septum. Fibers converge
+on the pterygoid in anteroventrolateral and posteroventrolateral
+directions. The posterior edge of the muscle is in contact with _M.
+protractor quadrati_ with which its fibers mingle. The insertion is
+fleshy on the posterior surface of the lateral half of the pterygoid to
+its articulation with the body of the quadrate (figs. 6, 8, 9, 11,
+13-20).
+
+~_M. depressor mandibulae superficialis medialis._~--The origin is
+fleshy from the lateral edge of the basioccipital where the muscle is
+attached to _Ligamentum depressor mandibulae_ and extends in a lateral
+direction to a point where the structures involved turn dorsad. The
+insertion is by fibers and a light aponeurosis on the crista that is
+situated on the posteroventromedial edge of the lower mandible.
+
+~_M. depressor mandibulae superficialis lateralis._~--The origin is
+fleshy from the squamosal region, slightly posteroventral to the origin
+of _M. adductor mandibulae externus superficialis_. A thin aponeurosis
+lies medial to the muscle fibers. The insertion is by means of an
+aponeurosis that becomes tendonlike along the posteroventrolateral
+crista and the posteriormost part of the ventral edge of the lower
+mandible.
+
+~_M. depressor mandibulae medialis._~--The origin is fleshy from the
+lateral and ventral surfaces of _Ligamentum depressor mandibulae_. The
+insertion is fleshy on the posterior surface of the lower mandible,
+posterodorsal to the insertions of _partes superficialis medialis et
+lateralis_ (figs. 4, 9, 10, 13 and 14).
+
+The parts of _M. depressor mandibulae_ are difficult to distinguish
+from one another because of considerable intermingling of fibers.
+
+~_M. pseudotemporalis superficialis._~--The origin is fleshy from the
+posterior wall of the orbit, dorsal to the foramen of the trigeminal
+nerve, lateral to the origin of _M. protractor quadrati_ and medial to
+_M. adductor mandibulae externus profundus_. The insertion is by means
+of an aponeurosis that bifurcates at the point of contact with the
+mandibular ramus of the trigeminal nerve, which is at the level of the
+orbital process of the quadrate (except in the Mourning Dove where the
+division is more anterior), and which inserts as two tendons on the
+dorsomedial edge of the lower mandible posterior to the insertion of
+_M. pseudotemporalis profundus_. The lateral tendon is superficial to
+the dorsomedial edge of _M. adductor mandibulae externus_, and
+converges with the aponeurosis of _pars profundus_ of that muscle and
+inserts with it on a tubercle near the dorsomedial edge of the
+mandible anterior to the insertion of _M. adductor mandibulae
+posterior_ as mentioned before. The anterior half of the medial tendon
+lies ventral to the lateral edge of _M. pseudotemporalis profundus_ and
+the mandibular ramus of the trigeminal nerve. All of the fibers of the
+muscle insert on the posteroventral surface of the aponeurosis before
+it divides. Part of _M. pseudotemporalis profundus_ also lies ventral
+to the medial tendon of _M. pseudotemporalis superficialis_ and, in
+effect, the tendon is imbedded in the substance of _M. pseudotemporalis
+profundus_ as it proceeds anteriorly. The trigeminal nerve leaves a
+slight impression on the ventral surface of the muscle near its origin
+(figs. 1, 3, 11, 13, 14, 15 and 16).
+
+~_M. adductor mandibulae posterior._~--The origin is fleshy from the
+anterodorsal and anterior surfaces of the quadrate body, from the
+anterodorsolateral, medial and anterior surfaces of the orbital process
+of the quadrate. The muscle also has an origin from the otic process of
+the quadrate, partly fleshy and partly by a slight aponeurosis. The
+insertion is fleshy on the dorsal and lateral surfaces of the mandible
+immediately anterior to the articulating surface. This muscle also has
+extensive insertion on the medial side of the lower mandible dorsal to
+the insertion of _M. pterygoideus dorsalis medialis_ and posterior to
+the origin of _M. pseudotemporalis profundus_ (figs. 1, 3, 5, 17, 18,
+19 and 20).
+
+The fibers of _M. pseudotemporalis profundus_ can be distinguished from
+the fibers of _M. adductor mandibulae posterior_ because the
+pterygoideus nerve passes between the two (Lakjar, 1926:55). Rooth
+(1953:255-256) considers as part of this muscle the ventral aponeurosis
+of _pars profundus_ of _M. adductor mandibulae externus_ and all the
+fibers ventral to it. But I could not justify the inclusion of that
+aponeurosis as part of _M. adductor mandibulae posterior_ in the doves
+because none of the fibers of _M. adductor mandibulae posterior_ as I
+have described it were attached to that particular aponeurosis.
+
+~_M. protractor quadrati._~--The origin is fleshy from the posterior
+wall of the orbit medial to the foramen of the trigeminal nerve and
+also medial to the origin of _M. pseudotemporalis superficialis_. The
+origin describes an arc in the horizontal plane until it reaches the
+interorbital septum and the optic nerve. The insertion is fleshy on the
+posteromedial edge of the body of the quadrate and the orbital process
+of the quadrate and on the otic process of the quadrate. The muscle
+also inserts on the ventromedial surface of the orbital process of the
+quadrate and the adjacent area of the body of the quadrate (figs. 5, 7,
+9, 11, 13-18).
+
+_M. protractor quadrati_ possesses many fibers that arise from _M.
+protractor pterygoidei_. Consequently, it is difficult to determine the
+exact extent of the origin or the insertion of either muscle.
+
+
+ACTION OF JAW MUSCLES
+
+~_M. pterygoideus ventralis._~--Contraction of this muscle retracts the
+upper mandible by moving the palatine posteriorly, and simultaneously
+adducts the lower mandible.
+
+~_M. pterygoideus dorsalis._~--This muscle functions in essentially the
+same manner as _M. pterygoideus ventralis_. The result of having a part
+of its origin on the pterygoid as well as on the palatine is to
+facilitate retraction of the upper mandible.
+
+~_M. adductor mandibulae._~--This is the chief adductor of the lower
+mandible and the muscle functions solely in that capacity. In birds
+having great crushing ability, this muscle is much larger and more
+powerful and the skull is reinforced behind the quadrate in order to
+withstand the pressure of the lower mandible against the quadrate
+during adduction (Sims, 1955:374 and Bowman, 1961:219-222).
+
+~_M. pseudotemporalis profundus._~--With origin and insertion on highly
+movable bones, this muscle, when it contracts, retracts the upper
+mandible and adducts the lower mandible. Like the pterygoid muscles,
+this muscle, by itself, would allow the bird to grasp objects by means
+of its mandibles. However, _M. pseudotemporalis profundus_ could
+produce a more powerful grip because it takes origin farther anteriorly
+on the lower mandible.
+
+~_M. protractor pterygoidei._~--Contraction of _M. protractor
+pterygoidei_ pulls the pterygoid anteromedially and causes it to slide
+forward along the sphenoidal rostrum. This action aids in protraction
+of the upper mandible.
+
+~_M. depressor mandibulae._~--The depressor of the lower mandible is
+the sole muscle other than _M. geniohyoideus_ involved in the function
+of abducting the lower jaw of doves. Its size can be correlated
+especially well with feeding habits of the bird. Other birds that force
+their closed mandibles into fruit, wood or the earth and then forcibly
+open them, belong to groups possessing enlarged depressors. Contraction
+of the muscle pulls the postarticular (retroarticular) process upward
+with the resultant downward movement of that part of the mandible which
+is anterior to the articulation. Since there is no "gaping" in doves
+the muscle is only large enough to overcome the inherent tone of the
+relaxed adductor muscles.
+
+In some non-passerine species as well as in certain passerines the
+muscle also serves to raise the upper jaw by acting on the quadrate,
+which is capable of rotating vertically on its otic process. Especially
+in the gapers, where resistance is offered near the tip of the lower
+mandible, contraction of the muscle pulls the entire mandible dorsad
+thus forcing the jugal and palatal struts forward (Zusi, 1959:537-539).
+The action supplements that of _Mm. protractor pterygoidei et quadrati_
+and is enhanced by anterior migration of the origin of _M. depressor
+mandibulae_.
+
+There is no lifting action involved in contraction of the depressor
+muscle in doves for two reasons--(A) the origin of the muscle is
+situated much too far posteriorly on the skull, and, more important,
+(B) the quadrate is not hinged for vertical movement. As will be
+discussed later, it moves only in a horizontal plane.
+
+~_M. pseudotemporalis superficialis._~--Like _M. adductor mandibulae_,
+this muscle performs only the one function of adducting the lower
+mandible, and like _M. pseudotemporalis profundus_ it is a synergist of
+that muscle.
+
+~_M. adductor mandibulae posterior._~--Although this muscle undoubtedly
+acts as an adductor of the lower mandible, I believe that, because of
+its disadvantageous insertion so near the articulation, its main
+function must be concerned with firming the mandible against the
+quadrate. This is to say that its function is partially that of a
+ligament.
+
+~_M. protractor quadrati._~--When _M. protractor quadrati_ contracts,
+the quadrate bone is swung medially. This action, as mentioned
+previously, results in protraction of the upper jaw, and, as a
+consequence, its action supplements the action of _M. protractor
+pterygoidei_.
+
+
+CRANIAL OSTEOLOGY
+
+The ability of most birds to protract the upper mandible, and the
+structure of the skull which enables them to do so are responsible for
+common reference to the skull as "kinetic" (Beecher, 1951a:412; Fisher,
+1955:175). The movement is effected by muscular action on a series of
+movable bones that exert their forward force on the upper mandible,
+which in turn swings on a horizontal hinge, the "naso-frontal hinge,"
+at the base of the beak. The bone initiating the movement is the
+quadrate, which is hinged posteriorly by its otic process and which
+ordinarily swings up or down depending on the muscle or muscles being
+contracted at any given moment. The upward swing of the quadrate pushes
+the jugal bar, which is attached to its lateral tip, along its
+longitudinal axis, in an anterodorsal direction, and the force is
+transferred to the upper mandible, which is thereby elevated. A
+synergetic mechanism is simultaneously initiated by the same bone--the
+quadrate. Since the quadrate body articulates with the pterygoid, the
+upward movement forces the pterygoid to slide along a ridge in the
+ventral midline of the cranium, the sphenoidal rostrum, thus pushing
+the palatine forward and exerting an upward push on the upper mandible.
+
+In the columbids the quadrate has a bifurcated otic process that
+functions as the hinge. The posterior tips of the forks are situated
+almost vertically (one above the other) and the movement of the
+quadrate is not so much up and down, or vertical, as it is horizontal
+(fig. 12). When the quadrate moves medially the upper mandible is
+protracted; a lateral movement results in retraction. There is a
+slight, almost negligible, upward movement of the quadrate. The
+movements of the various bony elements were observed on a skull that
+had been made flexible by boiling in water for a minute as suggested by
+Beecher (1951a:412).
+
+Also in the columbids the naso-frontal hinge is not constructed in the
+same manner as it is in many other birds as there is not a simple hinge
+across the entire base of the beak. In fact, there is no true hinge at
+all in the area of the nasals, but those bones are extremely thin and
+they bend or flex under pressure. Actually, the hinge is double or
+divided. One part is on either side of the nasals. The hinges are
+situated at the posterodorsal tips of two thin processes of the
+maxillary bones and the appearance is not unlike that of half a span of
+a suspension bridge having the hinges at the tops of the towers.
+Several other species of birds share this type of hinge construction
+with columbids.
+
+The movement of the lower jaw is, of course, the primary operation
+involved in opening the mouth. The lower jaw possesses a deep fossa at
+its posterior end, or on its posterodorsal surface, which articulates
+with the body of the quadrate bone. The length of that part of the
+mandible extending behind the articulation is directly correlated with
+the resistance offered the mandible in opening, since it is on the
+posterior extension that the depressor of the lower mandible inserts.
+The larger the muscle the more surface is needed for attachment. Also
+the added length of the mandible posterior to the articulation serves
+as a lever in opening the mandible, and the fulcrum is moved relatively
+farther forward.
+
+In birds lacking resistance to abduction of the lower mandible, as in
+doves, it is nevertheless necessary for a slight postarticular process
+to remain for the insertion of a small depressor muscle which, as
+mentioned previously, is necessary to counteract the relaxed adductor
+muscles of the lower jaw.
+
+There are many exceptions to the rule that birds have kinetic skulls,
+and usually a secondary fusion and reinforcement of bones around the
+hinge has limited or eliminated all movement. Sims (1955) describes the
+Hawfinch's immobile upper jaw, which is used as a powerful press in
+cracking the stones of fresh fruit. Skulls of woodpeckers have been
+modified somewhat in the same manner as a result of their foraging and
+nesting habits (Burt, 1930).
+
+The two most distantly related members of the genera under
+investigation are the White-winged Dove, _Zenaida asiatica_, and the
+Mourning Dove, _Zenaidura macroura_. They were chosen to demonstrate
+differences and likenesses in proportions of members of the genera.
+
+Ten measurements were taken on each skull, but simple observation
+reveals that, in relation to total length of the skull, the beak of the
+White-winged Dove is longer than that of the Mourning Dove. Tip of
+upper mandible to base of beak averaged 48.6 and 42.9 per cent of the
+total length of the skull in the White-winged Dove and Mourning Dove,
+respectively. The position of the jugal bar has remained about the same
+with respect to the cranial part of the skull, and the entire cranial
+part of the skull is almost the same shape in the species studied.
+
+Likewise, in the White-winged Dove the distance from the anterior tip
+of the lower mandible to the anterior part of _M. adductor mandibulae
+externus_ is relatively longer in relation to the length of the lower
+mandible than in the Mourning Dove. Finally, the position of the jugal
+with respect to the naso-frontal hinge is about the same in the two
+species.
+
+Measurements and calculations indicate that the longer beak of the
+White-winged Dove as compared with the Mourning Dove is a function of
+the beak itself, not of differences in other parts of the skull.
+Measurements of skulls of Eared and Zenaida doves support this view.
+
+
+OTHER MORPHOLOGICAL FEATURES
+
+In the species dissected, the only variable muscle that I consider
+significant in revealing relationships is _M. pseudotemporalis
+profundus_. It is markedly enlarged in the White-winged Dove in
+relation to the homologous muscle in the Mourning Dove. The muscle is
+enlarged in such a manner that a lateral expansion of its mass is
+apparent in superficial or dorsal view (compare figures 15 and 16).
+This, of course, indicates a muscle with powerful contraction, which
+has been unable to enlarge its circumference symmetrically because the
+eye is immediately dorsal to the muscle. Therefore it has expanded
+laterally. Ventral expansion is blocked by the presence of other
+muscles, and medially there is no surface for the insertion of
+additional fibers on the orbital process of the quadrate.
+
+The jaw musculature has been known for some time to be highly adaptive
+(Beecher, 1951a and b, 1953; Bowman, 1961; Burt, 1930; Engels, 1940 and
+Goodman and Fisher, 1962) and it would not be unreasonable, I think, to
+expect the jaw muscles of closely related species with similar habits
+to be similar. The beak of the White-winged Dove is longer in
+proportion to the length and height of the skull (exclusive of the
+beak) than is the beak of the Mourning Dove. The lengthened beak is
+probably an adaptation for nectar-feeding, which has been documented by
+McGregor, Alcorn and Olin (1962:263-264) while investigating
+pollinating agents of the Saguaro Cactus (_Cereus giganteus_), and by
+Gilman (1911:53) who observed the birds thrusting their bills into the
+flowers of the plant. Gilman indicated, however, that he could not be
+sure if the birds were seeking insects, pollen, or nectar. In any event
+the lengthened bill probably facilitates getting food by birds that
+probe parts of flowers. Hensley (1954:202) noted that both Mourning and
+White-winged doves were "exceptionally fond of this source of
+nourishment." But he also points out an "interesting correlation"
+between the presence of the white-wings in the desert and the flowering
+of the saguaro. During his studies the appearance of the first
+white-wing preceded the opening of the first saguaro flower by two
+days. The flowering and fruiting season lasted until August, the month
+of termination of the white-wing breeding season.
+
+Since Hensley makes the correlation solely with the white-wings, I
+assume that there is no other obvious correlation between plants and
+birds among the remainder of the avifauna of the desert. Probably the
+Mourning Dove has failed to adapt to nectar-feeding as yet, and the
+White-winged Dove is the primary exploiter of this food niche. It
+should be noted, also, that the head of the Mourning Dove is smaller
+than the white-wing's, and perhaps there is no need for an elongated
+beak for reaching deeply into the flowers.
+
+The lengthened bill should produce no difficulties in protraction of
+the upper mandible and depression of the lower for the reason that in
+the dove there is no known resistance offered to these movements. The
+genus _Icterus_ furnishes an example wherein resistance is met in the
+process of opening the mandibles; individuals of this genus thrust
+their closed bill into certain fruits and forcibly open their mandibles
+against the resistance of the pulp by strong protraction and
+depression, thus permitting the juices of the fruit to lake and
+ultimately to be consumed (Beecher, 1950:53). Beecher refers to the
+technique used in fruit-eating as "gaping." The result of gaping in
+_Icterus_ should be the presence of a more massive set of muscles
+concerned with protraction and depression than is found in non-gaping
+groups. Beecher found the situation to be exactly as expected in that
+genus and in other genera which also gape. Meadowlarks (_Sturnella_)
+and caciques (_Archiplanus_) gape and pry in soil and wood respectively
+(Beecher, 1951a:422 and 426).
+
+The lengthened beak would be a problem when the White-winged Dove
+attempted to pick up objects such as seeds, which do in fact constitute
+the largest percentage of its diet in spite of its nectar-feeding
+habit. A similar situation exists in the genus _Icterus_, which is
+primarily adapted for gaping even though it shows a preference for
+insects when they are abundant (Beecher, 1950:53). The lengthened beak
+could be compensated for by (A) migration of the anterior end of the
+jugal bar toward the rostral tip of the bill and away from the
+fronto-nasal hinge with a simultaneous enlargement of the adductor
+muscles of the lower mandible, or (B) enlargement of the one muscle
+that functions simultaneously as an efficient retractor of the upper
+mandible and adductor of the lower mandible, namely _M.
+pseudotemporalis profundus_. _Mm. pterygoideus dorsalis et lateralis_
+perform the same function, but because of their position on the lower
+mandible they, apparently, are stronger retractors of the upper
+mandible than they are adductors of the lower.
+
+It will be recalled that the jugal bar bears the same, or nearly the
+same, relationship to the cranium in the white-wing as it does in the
+Mourning Dove and that the heads, excluding the beaks of both species,
+are of nearly the same proportions. Also, _Mm. adductor mandibulae
+externus_ and _pseudotemporalis superficialis_, the chief adductor
+muscles of the lower mandible, were not noticeably enlarged in the
+white-wing. It is also important to note that other combinations of
+migration of bone and/or enlargement of muscles could successfully
+solve the problem of providing sufficient leverage for the proper
+functioning of the lengthened mandibles, but it is my thesis that the
+second alternative sufficed for seed-eating habits and that that is the
+adaptation that was established; it is, in fact, the only one present
+in the White-winged Dove.
+
+It is unlikely that this enlarged muscle and beak are the remains of
+another series of jaw muscles that have converged toward the condition
+in Mourning Doves. Columbids are almost unquestionably monophyletic,
+and two lines would have had to diverge and then converge. There is no
+evidence for such an evolutionary occurrence.
+
+
+GENERIC RELATIONSHIP
+
+An attempt will be made here to summarize all the available evidence,
+direct or indirect, which bears on the problem of relationship of these
+genera. The original dissections which are discussed in this report are
+only valuable as one more bit of evidence concerning one characteristic
+that aids in clarification of generic relationship, and it is only in
+conjunction with other evidence that any satisfactory conclusion may be
+forthcoming.
+
+
+Morphology
+
+My dissections demonstrated that, in relation to the size of the doves,
+the jaw musculature of all the specimens investigated was so nearly
+alike that only one major difference was detected. _M. pseudotemporalis
+profundus_ appeared to be enlarged in the White-winged Dove. This might
+have been predicted, since the white-wing was also shown to possess an
+elongated beak, presumably an adaptation for nectar-feeding, which
+would necessitate additional muscle development in order to compensate
+for the added length. Measurements recorded from several skulls
+indicated that the heads of the birds (excluding the beak) are nearly
+proportional.
+
+Perhaps plumage patterns are the most widely used characters for
+determining generic relationships of birds. Ridgway (1916:339-385)
+followed the columbid classification of Salvadori (1893) using plumage
+patterns and body proportions to distinguish between the genera. In the
+genus _Zenaidura_ he included the unique specimen _Zenaidura
+yucatanensis_, and he placed _auriculata_ in _Zenaida_. The
+White-winged Dove was referred to a separate genus, _Melopelia_. He
+described the genus _Zenaidura_ in the following manner:
+
+ "Plumage of head, neck and under parts soft and blended;
+ bare orbital space moderate, broadest beneath eyes.
+ Coloration plain, the proximal secondaries (sometimes
+ adjacent wing-coverts and scapulars also) spotted with
+ black; rectrices (except middle pair) with a black band
+ across postmedian portion, the apical portion paler gray
+ than basal portion, sometimes white; a small black
+ subauricular spot; adult males with head, neck and anterior
+ under parts more or less vinaceous and sides of neck glossed
+ with metallic purple."
+
+He noted that the plumage of _Zenaida_ was almost precisely as
+described for _Zenaidura_. Also, although all members of _Zenaida_
+reputedly possessed twelve rectrices, a characteristic of the genus, it
+was later found that _auriculata_ possessed fourteen rectrices. The
+species was promptly placed in the genus _Zenaidura_ by Peters
+(1934:213-215). In plumage and coloration, _Melopia_ was described as
+similar to _Zenaida_ and _Zenaidura_ but without black spots on the
+wings.
+
+The White-winged Dove also has twelve rectrices, but Bond (1940:53) and
+Goodwin (1958:330-334) considered the number and shape of rectrices to
+be of minor importance when compared to the homologous markings of the
+plumage. Goodwin stated that his conclusion was emphasized by the fact
+that the tail of _auriculata_ is intermediate in length and shape
+between those of _macroura_ and _aurita_. In summary Goodwin "lumped"
+the genera _Zenaida_ and _Zenaidura_ under the genus _Zenaida_.
+
+
+Nidification
+
+It has been adequately documented that members of these genera closely
+resemble one another in their nesting and egg-laying habits. Bent
+(1932:407, 417), Davie (1889:157), Goss (1891:242) and Nice (1922:466)
+have described the two, white eggs of the clutch of the Mourning Dove.
+They have also noted that their nests are composed mainly of twigs and
+may be constructed in trees, shrubs or on the ground. The Eared Dove
+has nearly identical habits (Bond, 1961:104), and a similar situation
+exists with the Zenaida Dove (Audubon, 1834:356; Bent, 1932:418-419).
+
+Like the other species, White-winged Doves lay two white or buffy eggs
+per clutch and build frail nests of sticks (Bent, 1932:431; Wetmore,
+1920:141; Baird, Brewer and Ridgway, 1905:377).
+
+The point to be made here is simply this: If the species in question
+are to be considered congeneric then it might reasonably be expected
+that they would display some similarity in nidification and egg-laying.
+If their habits varied considerably it would not necessarily mean that
+their relationship was more distant, but similarities can usually be
+considered indicative of affinities because they are the phenotypic
+expression of the partially unaltered genotype of the common ancestor.
+
+
+Interbreeding
+
+Intergeneric crosses of columbids in captivity are common, but in
+nature there is little evidence that even interspecific crosses occur.
+Only one apparent hybrid between members of the genus _Zenaida_ and
+genus _Zenaidura_ has ever been discovered. The individual was taken on
+the Yucatan peninsula of Mexico, and was described and named as a new
+species (_Zenaidura yucatanensis_).
+
+Salvadori (1893:373), Ridgway (1916:353) and Peters (1934:213-215)
+agree that _Zenaidura yucatanensis_ Lawrence is a hybrid between
+_Zenaidura macroura marginella_ and _Zenaida aurita yucatanensis_.
+Ridgway (1916:355), however, notes that "... If _Zenaidura
+yucatanensis_ Lawrence should prove to be really a distinct species,
+and not a hybrid ... unquestionably _Zenaida_ and _Zenaidura_ can not
+be separated generically, since the former is in every way exactly
+intermediate between the two groups." In the event that the unique type
+is a hybrid, the very fact of its existence supports the hypothesis
+that the genera are more closely related than is currently recognized.
+
+
+Serology
+
+There have been no investigations having as their sole purpose the
+clarification of the relationship of the genera _Zenaida_ and
+_Zenaidura_. But some work has involved the comparison of the antigenic
+content of individual columbids with the antigenic content of a member
+of another species of the same family.
+
+Irwin and Miller (1961) tested, along with other columbids, members of
+_Zenaida_ and _Zenaidura_ for presence of, 1) species-specific antigens
+of _Columba guinea_ (in relation to _Columba livia_) which are
+designated A, B, C and E, and, 2) species-specific antigens of _C.
+livia_ (in relation to _C. guinea_) which are designated A´, B´, C´ and
+E´.
+
+In the first test all five species of _Zenaida_ and _Zenaidura_
+possessed antigens A and C, and all but _auriculata_ possessed E. None
+of the species gave evidence of the presence of the B antigen of _C.
+guinea_ in their blood. In the latter test only _macroura_ had A´, only
+_asiatica_ had B´ (_aurita_ was not tested for B´), and none had C´ or
+E´.
+
+These results would indicate that the five species are similar
+regarding antigenic content of the blood, and the variation is not
+consistent within one or the other genus as presently known.
+
+
+SUMMARY AND CONCLUSION
+
+The avian genus _Zenaida_ is currently considered to be distinct from
+the genus _Zenaidura_ by most columbid taxonomists. The jaw muscles of
+six Mourning Doves (_Zenaidura_) and five White-winged Doves
+(_Zenaida_) were investigated as to differences and similarities that
+might clarify the relationships of the genera. The sizes and
+proportions of skulls were also considered in 37 Mourning and
+White-winged doves and two Eared Doves. Larger size of _M.
+pseudotemporalis profundus_, the muscle that functions simultaneously
+as an adductor of the lower jaw and retractor of the upper jaw, in the
+White-winged Dove was the character found in the jaw musculature that
+could be used to support the contention that _Zenaidura_ and _Zenaida_
+represent distinct genera. Larger size of this muscle in the white-wing
+seems to be related to its elongated beak. The long beak apparently is
+used for nectar-feeding in flowers of the Saguaro Cactus.
+
+Excluding the beak, skulls of the white-wing and Mourning doves are of
+nearly the same shape. Previous investigators have shown that in
+_Zenaida_ and _Zenaidura_ plumage patterns are similar, nesting habits
+and eggs are nearly identical, blood proteins are similar, and one
+"intergeneric" hybridization in nature is known.
+
+Consequently, it is concluded that species of the two alleged genera
+are congeneric, and I agree with Goodwin (1958) that the genus
+_Zenaida_ (Bonaparte, 1838:41) should include the Mourning Dove, Eared
+Dove, Socorro Dove, Zenaida Dove, and White-winged Dove. Their Latin
+binomina are _Zenaida macroura_, _Zenaida auriculata_, _Zenaida
+graysoni_, _Zenaida aurita_, and _Zenaida asiatica_, respectively.
+
+[Illustration: FIG. 1. Medial view of left ramus of lower
+mandible of Mourning Dove. × 2-1/2.
+
+FIG. 2. Lateral view of right ramus of lower mandible of
+Mourning Dove. × 2-1/2.]
+
+[Illustration: FIG. 3. Dorsal view of lower mandible of
+Mourning Dove. × 2-1/2.
+
+FIG. 4. Ventral view of lower mandible of Mourning Dove.
+× 2-1/2.]
+
+[Illustration: FIG. 5. Dorsal view of right quadrate of
+Mourning Dove. × 5.
+
+FIG. 6. Dorsal view of right pterygoid of Mourning Dove. × 5.
+
+FIG. 7. Ventral view of right quadrate of Mourning Dove. × 5.
+
+FIG. 8. Ventral view of right pterygoid of Mourning Dove. × 5.]
+
+[Illustration: FIG. 9. Right lateral view of skull of Mourning
+Dove. × 2-1/2.
+
+FIG. 10. Ventral view of skull of Mourning Dove. × 2-1/2.]
+
+[Illustration: FIG. 11. Cross section of skull of Mourning Dove;
+anterior view. × 2-1/2.
+
+FIG. 12. Dorsal view of right quadrate of Mourning Dove showing
+movement which protracts the upper mandible (broken line). × 5.]
+
+[Illustration: FIG. 13. Right lateral view of the jaw musculature of
+the White-winged Dove; superficial layer, × 5.
+
+FIG. 14. Right lateral view of the jaw musculature of the Mourning
+Dove; superficial layer. × 5.]
+
+[Illustration: FIG. 15. Dorsal view of the jaw musculature of the
+White-winged Dove (right side); superficial layer. × 5.
+
+FIG. 16. Dorsal view of the jaw musculature of the Mourning Dove
+(right side); superficial layer. × 5.]
+
+[Illustration: FIG. 17. Dorsal view of the jaw musculature of the
+White-winged Dove (right side); middle layer. × 5.
+
+FIG. 18. Dorsal view of the jaw musculature of the Mourning Dove
+(right side); middle layer. × 5.]
+
+[Illustration: FIG. 19. Dorsal view of the jaw musculature of the
+White-winged Dove (right side); deep layer. × 5.
+
+FIG. 20. Dorsal view of the jaw musculature of the Morning Dove (right
+side); deep layer. × 5.]
+
+[Illustration: FIG. 21. Ventral view of the jaw musculature of the
+White-winged Dove (_M. depressor mandibulae_ not shown). × 5.
+
+FIG. 22. Ventral view of the jaw musculature of the Mourning Dove
+(_M. depressor mandibulae_ not shown). × 5.]
+
+
+
+
+LITERATURE CITED
+
+
+ADAMS, L. A.
+ 1919. A memoir on the phylogeny of the jaw muscles in recent and
+ fossil vertebrates. Annals New York Acad. Sci., 28:51-166.
+
+AUDUBON, J. J.
+ 1834. Ornithological biography. Vol. II. Adam & Charles Black,
+ Edinburgh, xxxii + 588 pp.
+
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+ passerine birds. Auk, 76:537-539.
+
+
+_Transmitted June 3, 1963._
+
+
+
+
+ * * * * *
+
+Transcriber's Notes
+
+Italicized text is shown within _underscores_.
+
+Bold italicized text is shown within ~_tildes and underscores_~.
+
+
+
+
+
+
+
+
+End of the Project Gutenberg EBook of Jaw Musculature of the Mourning and
+White-winged Doves, by Robert L. Merz
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+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: Jaw Musculature of the Mourning and White-winged Doves
+
+Author: Robert L. Merz
+
+Release Date: April 17, 2010 [EBook #32018]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK JAW MUSCULATURE--DOVES ***
+
+
+
+
+Produced by Chris Curnow, Joseph Cooper, Diane Monico, and
+the Online Distributed Proofreading Team at
+https://www.pgdp.net
+
+
+
+
+
+
+</pre>
+
+
+
+
+
+<p class="title"><span class="smcap">University of Kansas Publications</span><br />
+<span class="smcap">Museum of Natural History</span><br /><br />
+
+Volume 12, No. 12, pp. 521-551, 22 figs.<br />
+October 25, 1963</p>
+<hr style="width: 25%;" />
+
+<h1>Jaw Musculature<br />
+Of the Mourning and White-winged Doves</h1>
+
+
+<p class="title">BY<br /><br />
+
+<big>ROBERT L. MERZ</big><br /><br /></p>
+
+
+<p class="title"><span class="smcap">University of Kansas</span><br />
+<span class="smcap">Lawrence</span><br />
+1963<br />
+</p>
+<hr style="width: 65%;" />
+
+
+
+<p class="title">
+<span class="smcap">University of Kansas Publications, Museum of Natural History</span><br />
+<br />
+Editors: E. Raymond Hall, Chairman, Henry S. Fitch,<br />
+Theodore H. Eaton, Jr.<br />
+<br />
+Volume 12, No. 12, pp. 521-551, 22 figs.<br />
+Published October 25, 1963<br />
+<br />
+<br />
+<span class="smcap">University of Kansas</span><br />
+Lawrence, Kansas<br />
+<br />
+<br />
+<small>PRINTED BY<br />
+JEAN M. NEIBARGER, STATE PRINTER<br />
+TOPEKA, KANSAS<br />
+1963<br />
+<br />
+29-7865<br />
+</small></p>
+
+
+
+<hr style="width: 65%;" /><p><span class="pagenum"><a name="Page_523" id="Page_523">[Pg 523]</a></span></p>
+<h1>
+Jaw Musculature<br />
+Of the Mourning and White-winged Doves<br />
+</h1>
+
+<p class="center">BY<br /><br />
+
+ROBERT L. MERZ</p>
+
+
+<p>For some time many investigators have thought that the genus
+<i>Zenaida</i>, which includes the White-winged and Zenaida doves, and
+the genus <i>Zenaidura</i>, which includes the Mourning, Eared, and
+Socorro doves (Peters, 1937:83-88), are closely related, perhaps
+more closely than is indicated by separating the several species
+into two genera. It is the purpose of this paper to report investigations
+on the musculature of the jaw of doves with the hope that,
+together with the results of other studies, the relationships of the
+genera <i>Zenaida</i> and <i>Zenaidura</i> can be elucidated.</p>
+
+
+<h2>METHODS AND MATERIALS</h2>
+
+<p>In order to determine in each species the normal pattern of musculature
+of the jaws, heads of 13 specimens of doves were dissected (all material is in
+the Museum of Natural History of The University of Kansas): White-winged
+Doves (<i>Zenaida asiatica</i>), 40323, 40324, 40328, 40392, 40393; Zenaida Doves
+(<i>Z. aurita</i>), 40399, 40400; Mourning Doves (<i>Zenaidura macroura</i>), 40326,
+40394, 40395, 40396, 40397, 40398.</p>
+
+<p>Thirty-seven skulls from the collection of the Museum of Natural History
+of The University of Kansas and two skulls from the United States National
+Museum were measured. The measurements are on file in the Library of The
+University of Kansas in a dissertation deposited there by me in 1963 in partial
+fulfillment of requirements for the degree of Master of Arts in Zoology. Specimens
+used were: White-winged Doves, KU 19141, 19142, 19143, 19144,
+19145, 19146, 19147, 23138, 23139, 24337, 24339, 24341, 23592, 23593,
+24340, 31025, 31276; Mourning Doves, KU 14018, 14781, 15347, 15533,
+15547, 15550, 15662, 15778, 15872, 16466, 17782, 17786, 17788, 17795,
+19153, 19242, 20321, 21669, 22394, 22715; Eared Doves (<i>Zenaidura auriculata</i>),
+USNM 227496, 318381. Additionally, the skulls of the Zenaida Doves
+mentioned above were measured. All measurements were made with a dial
+caliper and read to tenths of a millimeter.</p>
+
+
+<h2>ACKNOWLEDGMENTS</h2>
+
+<p>My appreciation is extended to Professor Richard F. Johnston, who advised
+me during the course of this study, and to Professors A. Byron Leonard and
+Theodore H. Eaton for critically reading the manuscript.</p>
+
+<p>I would like also to acknowledge the assistance of Dr. Robert M. Mengel
+and Mr. Jon C. Barlow for suggestions on procedure, and Mr. William C.
+Stanley, who contributed specimens of Mourning Doves for study. Mr. Thomas<span class="pagenum"><a name="Page_524" id="Page_524">[Pg 524]</a></span>
+H. Swearingen offered considerable advice on production of drawings and
+Professor E. Raymond Hall suggested the proper layout of the same and gave
+editorial assistance otherwise, as also did Professor Johnston.</p>
+
+
+<h2>MYOLOGY</h2>
+
+<p>The jaw musculature of doves is not an imposing system. The
+eating habits impose no considerable stress on the muscles; the
+mandibles are not used for crushing seeds, spearing, drilling, gaping,
+or probing as are the mandibles of many other kinds of birds.
+Doves use their mandibles to procure loose seeds and grains, which
+constitute the major part of their diet (Leopold, 1943; Kiel and
+Harris, 1956: 377; Knappen, 1938; Jackson, 1941), and to gather
+twigs for construction of nests. Both activities require but limited
+gripping action of mandibles. The crushing habit of a bird such as
+the Hawfinch (<i>Coccothraustes coccothraustes</i>), on the other hand,
+involves extremely powerful gripping (see, for example, Sims,
+1955); the contrast is apparent in the development of the jaw musculature
+in the two types. Consequently, it is not surprising to find a
+relatively weak muscle mass in the jaw of doves, and because the
+musculature is weak there are few pronounced osseous fossae,
+cristae and tubercles. As a result, the bones, in addition to being
+small in absolute size, are relatively weaker when compared to
+skulls of birds having more distinctive feeding habits which require
+more powerful musculature.</p>
+
+<p>The jaw muscles of the species dissected for this study are, in
+gross form, nearly identical from one species to another. Thus, a
+description of the pertinent myology of each species is unnecessary;
+one basic description is hereby furnished, with remarks on the
+variability observed between the species.</p>
+
+<p>The terminology adopted by me for the jaw musculature is in
+boldfaced italic type. Synonyms are in italic type and are the
+names most often used by several other writers.</p>
+
+<div class="blockquot"><p><b><i>M. pterygoideus ventralis</i></b>: part of Mm. pterygoidei, Gadow, 1891:323-325,
+table 26, figs. 1, 2, 3 and 4, and table 27, fig. 3&mdash;part of M. pterygoideus
+internus, Shufeldt, 1890:20, figs. 3, 5, 6, 7 and 11&mdash;part of M. adductor
+mandibulae internus, Edgeworth, 1935:58, figs. 605c and 607&mdash;part of
+M. pterygoideus anterior, Adams, 1919:101, pl. 8, figs. 2 and 3.</p>
+
+<p><b><i>M. pterygoideus dorsalis:</i></b> part of Mm. pterygoidei, Gadow, 1891:323-325,
+table 26, fig. 7 and table 27, figs. 1 and 3&mdash;part of M. pterygoideus
+internus, Shufeldt, 1890:20&mdash;part of M. adductor mandibulae internus,
+Edgeworth, 1935:58, fig. 605c&mdash;? part of M. pterygoideus anterior,
+Adams, 1919:101, pl. 8, figs. 2 and 3.</p>
+
+<p><b><i>M. adductor mandibulae externus:</i></b> <i>a</i>) <b><i>pars superficialis:</i></b> parts 1 and 2 of
+M. temporalis, Gadow, 1891:320-321&mdash;part of M. temporal, Shufeldt,
+1890:16, figs. 5 and 7&mdash;part of M. adductor mandibulae externus, Edgeworth,<span class="pagenum"><a name="Page_525" id="Page_525">[Pg 525]</a></span>
+1935:58-60&mdash;M. capiti-mandibularis medius and profundus,
+Adams, 1919:101, pl. 8, fig. 1.</p>
+
+<p><i>b</i>) <b><i>pars medialis:</i></b> ? parts 1, 2 and 3 of M. temporalis, Gadow, 1891:320-322&mdash;part
+of M. masseter and ? part of M. temporal, Shufeldt, 1890:16-18,
+figs. 5, 6, 7 and 11&mdash;part of M. adductor mandibulae externus,
+Edgeworth, 1935:58-60&mdash;M. capiti-mandibularis superficialis, first part,
+Adams, 1919:100-101, pl. 8, fig. 1.</p>
+
+<p><i>c</i>) <b><i>pars profundus:</i></b> part 2 of M. temporalis, Gadow, 1891:321, table 27,
+fig. 2&mdash;part of M. temporal and ? part of M. masseter, Shufeldt, 1890:16-18&mdash;part
+of M. adductor mandibulae externus, Edgeworth, 1935:58-60&mdash;?
+part of M. capiti-mandibularis medius and all of pars superficialis,
+second part, Adams, 1919:100-101.</p>
+
+<p><b><i>M. pseudotemporalis profundus:</i></b> M. quadrato-maxillaris, Gadow, 1891:322-323&mdash;M.
+pterygoideus externus, Shufeldt, 1890:20-21, figs. 3, 5 and
+11&mdash;part of M. adductor mandibulae medius, Edgeworth, 1935:58-59&mdash;?
+part of M. pterygoideus posterior, Adams, 1919:101, pl. 8, figs. 2 and 3.</p>
+
+<p><b><i>M. protractor pterygoidei:</i></b> part 4b of M. temporalis, Gadow, 1891: 322-323,
+table 27, fig. 4&mdash;part of M. entotympanious, Shufeldt, 1890:19-20,
+figs. 3 and 11&mdash;part of M. spheno-pterygo-quadratus, Edgeworth, 1935:57.</p>
+
+<p><b><i>M. depressor mandibulae:</i></b> M. digastricus s. depressor mandibulae, Gadow,
+1891:318-319&mdash;M. biventer maxillae, Shufeldt, 1890:18-19, figs. 3, 4,
+5, 6, 7 and 11.</p>
+
+<p><b><i>M. pseudotemporalis superficialis:</i></b> M. spheno-maxillaris, Gadow, 1891:323&mdash;part
+of M. temporal, Shufeldt, 1890:16&mdash;part of M. pseudotemporalis,
+Hofer, 1950:468-477&mdash;part of M. adductor mandibulae medius, Edgeworth,
+1935:277.</p>
+
+<p><b><i>M. adductor mandibulae posterior:</i></b> ? part of M. temporal, Shufeldt, 1890:16&mdash;part
+of M. adductor mandibulae medius, Edgeworth, 1935:58-59&mdash;?
+part of M. pterygoideus posterior, Adams, 1919:101, pl. 8, figs. 2 and 3.</p>
+
+<p><b><i>M. protractor quadrati:</i></b> part 4a of M. temporalis, Gadow, 1891:322-323,
+table 27, fig. 4&mdash;part of M. entotympanicus, Shufeldt, 1890:19-20, figs. 3
+and 11&mdash;part of M. spheno-pterygo-quadratus, Edgeworth, 1935:57.</p></div>
+
+<p>The terminology adopted by me is that of Lakjar (1926) except that the
+divisions of <i>M. depressor mandibulae</i> are designated by the Latinized equivalents
+of the names used by Rooth (1953:261-262).</p>
+
+<p><b><i>M. pterygoideus ventralis lateralis.</i></b>&mdash;The origin is fleshy and by aponeurosis
+on the ventral side of the palatine anterior to the palatine fossa. The insertion
+is fleshy on the ventromedial surface of the lower mandible and continues
+along the anteromedial surface of the internal angular process to its distal tip.
+A few fibers leave <i>pars lateralis</i> and insert on an aponeurosis which receives
+also all the fibers of <i>M. pterygoideus dorsalis lateralis</i>. The latter fact may
+have prompted Rooth (1953:257) to make the statement that the fibers
+originating on the dorsal part of the palatine inserted more laterally than those
+originating on the ventral side. Rooth worked with <i>Columba palumbus</i>, the
+Woodpigeon, and his description concerned <i>M. adductor mandibulae internus
+pterygoideus</i>, which is composed of <i>Mm. pterygoideus ventralis et dorsalis</i>
+of Lakjar (1926). His assertion that ventral fibers, that is to say, fibers arising
+on the ventral surface of the palatine, insert medially does not appear to be
+completely true for doves.</p>
+
+<p>Aponeuroses cover most of the lower surface of the muscle and one or two
+nerves extend into the substance of the muscle. The nerves run from the<span class="pagenum"><a name="Page_526" id="Page_526">[Pg 526]</a></span>
+anterior edge of <i>M. pterygoideus dorsalis medialis</i> and farther posteriorly from
+a separation in the muscle.</p>
+
+<p><b><i>M. pterygoideus ventralis medialis.</i></b>&mdash;The origin is by aponeurosis from
+the ventral surface of the palatine and fleshy from the palatine fossa. The
+aponeurosis is the same that gives origin to the fibers of <i>pars lateralis</i>. Part
+of the aponeurosis becomes tendonlike in the middle of <i>M. pterygoideus ventralis</i>
+and separates its two divisions. The insertion is fleshy on the lower
+one-third of the anterior surface of the internal angular process of the lower
+mandible, and by two tendons on the distal tip of that process. Many of the
+fibers of <i>pars medialis</i> insert on the tendons. The fibers at their insertion are
+not distinctly separate from those of <i>pars lateralis</i> and there is considerable
+mingling of the fibers. Consequently, the medial part of <i>M. pterygoideus
+ventralis</i> cannot be removed as a part distinct from the lateral part (figs. <a href="#figs1-2">1</a>,
+<a href="#figs3-4">4</a>, <a href="#figs9-10">10</a>, <a href="#figs21-22">21</a> and <a href="#figs21-22">22</a>).</p>
+
+<p>Ordinarily <i>M. pterygoideus ventralis</i> does not cross the ventral edge of the
+lower mandible, but in one white-wing the muscle was slightly expanded on
+the right side and it could be seen in lateral view. The homologous muscle
+in <i>Columba palumbus</i> apparently is consistently visible in lateral view. (See
+Rooth, 1953, fig. 6.)</p>
+
+<p><b><i>M. pterygoideus dorsalis medialis.</i></b>&mdash;The origin is fleshy on the dorsolateral
+surface of the palatine immediately anterior to the pterygoid and also on the
+anterior, dorsolateral, posterior and ventromedial surfaces of the pterygoid.
+The insertion is fleshy on the ventromedial surface of the lower mandible and
+the anterior surface of the internal angular process immediately dorsal to the
+insertion of <i>M. pterygoideus ventralis lateralis</i>.</p>
+
+<p><b><i>M. pterygoideus dorsalis lateralis.</i></b>&mdash;The origin is fleshy from the dorsolateral
+surface of the palatine, anterior to the origin of <i>pars medialis</i> and the
+insertion is by means of an aponeurosis on the medial surface of the lower
+mandible, lateral to the insertion of <i>M. pterygoideus ventralis lateralis</i>. The
+aponeurosis crosses the medial side of the insertion of <i>M. pterygoideus dorsalis
+medialis</i>. The fibers run in a posteroventrolateral direction and insert on the
+ventromedial side of the aponeurosis (figs. <a href="#figs1-2">1</a>, <a href="#figs5-8">6</a>, <a href="#figs5-8">8</a>, <a href="#figs9-10">9</a>, <a href="#figs13-14">13</a>-<a href="#figs21-22">22</a>).</p>
+
+<p>In one individual, a Mourning Dove, the origin of <i>pars lateralis</i> of <i>M. pterygoideus
+dorsalis</i> extended to the pterygoid. With this one exception the
+muscle was uniform throughout the several species.</p>
+
+<p><b><i>M. adductor mandibulae externus.</i></b>&mdash;This is the most complex muscle in
+the jaw owing to its system of tendons and aponeuroses. Three divisions of
+this muscle were described by Lakjar (1926:45-46) and the divisions appear
+to be distinguishable in the doves, but there is no clear line of demarcation
+for any of the parts and the following description is based upon my own attempts
+to delineate the muscle.</p>
+
+<p><b><i>M. adductor mandibulae externus superficialis.</i></b>&mdash;The origin is fleshy from
+the most lateral area of the temporal fossa. Dorsally the origin is bounded by
+the base of the postorbital process and ventrally by the temporal process. The
+fibers converge upon a tendon that passes beneath the postorbital ligament
+and runs anteriorly among the fibers of <i>pars profundus</i>. The insertion is
+tendinous on the dorsal surface of the lower mandible in common with the
+dorsal aponeurosis of <i>pars profundus</i>. The insertion is immediately anterior<span class="pagenum"><a name="Page_527" id="Page_527">[Pg 527]</a></span>
+to the ventral aponeurosis of <i>pars profundus</i> near the medial edge of the
+dorsal surface on a tubercle at the posterior end of the dorsal ridge of the
+lower mandible.</p>
+
+<p><b><i>M. adductor mandibulae externus medialis.</i></b>&mdash;The origin is by a flat, heavy
+tendon from the temporal process. The tendon is attached almost vertically
+on the temporal process. It twists approximately 130&deg; as it runs anteriorly,
+and becomes a thin aponeurosis, which gives rise on its dorsal and ventral
+surfaces to many fibers that insert in a fan-shaped area on the mandibular
+fossa. Fibers from the dorsal and dorsomedial sides of the heavy tendon run
+rostrad and insert on the ventral surface of the dorsal aponeurosis of <i>pars
+profundus</i>. From the ventral surface the most posterior fibers converge on
+an aponeurosis that inserts on a transverse crista on the dorsal surface of the
+mandible immediately lateral to the ventral aponeurosis of <i>pars profundus</i> and
+dorsal to the insertion of <b><i>M. adductor mandibulae posterior</i></b>. The more anterior
+fibers insert fleshily on the mandibular fossa. The tendon of origin is
+actually one with the ventral aponeurosis of <i>pars profundus</i>, which is situated
+in a horizontal plane. The insertion is primarily a fleshy attachment on the
+mandibular fossa. Some of the fibers that arise on the dorsomedial and
+lateral surfaces of the tendon of origin attach to another tendon, which inserts
+in the midline of the mandibular fossa on a small tubercle near the anterior
+end. Also, there is insertion by an aponeurosis anterior to <i>M. adductor mandibular
+posterior</i> as stated above. Fibers attach to the dorsal and ventral side
+of the aponeurosis.</p>
+
+<p><b><i>M. adductor mandibulae externus profundus.</i></b>&mdash;The origin is fleshy from
+the medial surface of the temporal fossa, the posterior wall of the orbit and
+the otic process of the quadrate. The origin is bounded laterally by the
+origin of <i>pars superficialis</i> and medially by the origin of <i>M. pseudotemporalis
+superficialis</i>. Ventrally the muscle lies against its own ventral aponeurosis,
+which originates on the posterior wall of the orbit immediately above the articulation
+of the otic process of the quadrate, and which also receives many fibers
+from the surface of the quadrate. The insertion is primarily by means of
+two aponeuroses. The most dorsal aponeurosis inserts on a tubercle at the
+posterior tip of the dorsal edge of the mandible. The lateral tendon of
+<i>M. pseudotemporalis superficialis</i> converges with the aponeurosis. It is superficial
+and there are no fibers on its dorsal surface. The ventral aponeurosis
+inserts on a crista immediately below the insertion of the dorsal aponeurosis.
+It receives fibers on its ventral surface from the otic process of the quadrate,
+and on its dorsal surface gives rise to fibers that insert on the dorsal aponeurosis
+(figs. <a href="#figs1-2">2</a>, <a href="#figs3-4">3</a>, <a href="#figs5-8">5</a>, <a href="#figs9-10">9</a>, <a href="#figs9-10">10</a>, <a href="#figs11-12">11</a>, <a href="#figs13-14">13</a>-<a href="#figs17-18">18</a>).</p>
+
+<p>The tendon of insertion of <i>pars medialis</i> of <i>M. adductor mandibulae externus</i>
+does not become a superficial aponeurosis posteriorly in the Zenaida Dove as
+it does in the Mourning and White-winged doves.</p>
+
+<p><b><i>M. pseudotemporalis profundus.</i></b>&mdash;The origin is fleshy from the medial and
+partially from the dorsal surface of the lower mandible. The origin is almost
+completely anterior to and partly dorsal and ventral to the medial (most
+anterior) insertion of <i>M. pseudotemporalis superficialis</i>. The anterior margin
+of the origin is at the point where the mandibular ramus of the trigeminal
+nerve enters the mandible. Posteriorly the origin is bounded by the insertion<span class="pagenum"><a name="Page_528" id="Page_528">[Pg 528]</a></span>
+of <i>M. adductor mandibulae posterior</i>, and ventrally by a ridge that is situated
+about halfway down the medial side of the mandible. The insertion is by
+aponeurosis on the tip of the orbital process of the quadrate and fleshily on
+the anterior surface of the same process. The aponeurosis extends about
+three-fifths of the distance along the muscle and it is dorsal or superficial
+to all of the fibers. Many fibers insert on the ventral side of the aponeurosis
+(figs. <a href="#figs1-2">1</a>, <a href="#figs5-8">5</a>, <a href="#figs13-14">13</a>, <a href="#figs13-14">14</a>, <a href="#figs15-16">15</a>, <a href="#figs15-16">16</a>, <a href="#figs21-22">21</a> and <a href="#figs21-22">22</a>).</p>
+
+<p>This muscle is the most variable of all the jaw muscles. In the Mourning
+Dove the muscle appears rather slender in dorsal view and in the White-winged
+Dove has an enlarged lateral belly that gives the appearance of a
+thicker muscle. In the Zenaida Dove <i>M. pseudotemporalis profundus</i> is intermediate
+in shape between those of the other two species. This muscle will be
+discussed in detail later.</p>
+
+<p><b><i>M. protractor pterygoidei.</i></b>&mdash;The origin is fleshy from the junction of the
+sphenoidal rostrum and the interorbital septum. Fibers converge on the
+pterygoid in anteroventrolateral and posteroventrolateral directions. The posterior
+edge of the muscle is in contact with <i>M. protractor quadrati</i> with which
+its fibers mingle. The insertion is fleshy on the posterior surface of the lateral
+half of the pterygoid to its articulation with the body of the quadrate (figs.
+<a href="#figs5-8">6</a>, <a href="#figs5-8">8</a>, <a href="#figs9-10">9</a>, <a href="#figs11-12">11</a>, <a href="#figs13-14">13</a>-<a href="#figs19-20">20</a>).</p>
+
+<p><b><i>M. depressor mandibulae superficialis medialis.</i></b>&mdash;The origin is fleshy from
+the lateral edge of the basioccipital where the muscle is attached to <i>Ligamentum
+depressor mandibulae</i> and extends in a lateral direction to a point
+where the structures involved turn dorsad. The insertion is by fibers and a
+light aponeurosis on the crista that is situated on the posteroventromedial edge
+of the lower mandible.</p>
+
+<p><b><i>M. depressor mandibulae superficialis lateralis.</i></b>&mdash;The origin is fleshy from
+the squamosal region, slightly posteroventral to the origin of <i>M. adductor mandibulae
+externus superficialis</i>. A thin aponeurosis lies medial to the muscle
+fibers. The insertion is by means of an aponeurosis that becomes tendonlike
+along the posteroventrolateral crista and the posteriormost part of the ventral
+edge of the lower mandible.</p>
+
+<p><b><i>M. depressor mandibulae medialis.</i></b>&mdash;The origin is fleshy from the lateral
+and ventral surfaces of <i>Ligamentum depressor mandibulae</i>. The insertion is
+fleshy on the posterior surface of the lower mandible, posterodorsal to the
+insertions of <i>partes superficialis medialis et lateralis</i> (figs. <a href="#figs3-4">4</a>, <a href="#figs9-10">9</a>, <a href="#figs9-10">10</a>, <a href="#figs13-14">13</a> and <a href="#figs13-14">14</a>).</p>
+
+<p>The parts of <i>M. depressor mandibulae</i> are difficult to distinguish from one
+another because of considerable intermingling of fibers.</p>
+
+<p><b><i>M. pseudotemporalis superficialis.</i></b>&mdash;The origin is fleshy from the posterior
+wall of the orbit, dorsal to the foramen of the trigeminal nerve, lateral to the
+origin of <i>M. protractor quadrati</i> and medial to <i>M. adductor mandibulae externus
+profundus</i>. The insertion is by means of an aponeurosis that bifurcates
+at the point of contact with the mandibular ramus of the trigeminal nerve,
+which is at the level of the orbital process of the quadrate (except in the
+Mourning Dove where the division is more anterior), and which inserts as two
+tendons on the dorsomedial edge of the lower mandible posterior to the
+insertion of <i>M. pseudotemporalis profundus</i>. The lateral tendon is superficial
+to the dorsomedial edge of <i>M. adductor mandibulae externus</i>, and converges
+with the aponeurosis of <i>pars profundus</i> of that muscle and inserts with it on<span class="pagenum"><a name="Page_529" id="Page_529">[Pg 529]</a></span>
+a tubercle near the dorsomedial edge of the mandible anterior to the insertion
+of <i>M. adductor mandibulae posterior</i> as mentioned before. The anterior half
+of the medial tendon lies ventral to the lateral edge of <i>M. pseudotemporalis
+profundus</i> and the mandibular ramus of the trigeminal nerve. All of the
+fibers of the muscle insert on the posteroventral surface of the aponeurosis
+before it divides. Part of <i>M. pseudotemporalis profundus</i> also lies ventral to
+the medial tendon of <i>M. pseudotemporalis superficialis</i> and, in effect, the
+tendon is imbedded in the substance of <i>M. pseudotemporalis profundus</i> as it
+proceeds anteriorly. The trigeminal nerve leaves a slight impression on the
+ventral surface of the muscle near its origin (figs. <a href="#figs1-2">1</a>, <a href="#figs3-4">3</a>, <a href="#figs11-12">11</a>, <a href="#figs13-14">13</a>, <a href="#figs13-14">14</a>, <a href="#figs15-16">15</a> and <a href="#figs15-16">16</a>).</p>
+
+<p><b><i>M. adductor mandibulae posterior.</i></b>&mdash;The origin is fleshy from the anterodorsal
+and anterior surfaces of the quadrate body, from the anterodorsolateral,
+medial and anterior surfaces of the orbital process of the quadrate. The
+muscle also has an origin from the otic process of the quadrate, partly fleshy
+and partly by a slight aponeurosis. The insertion is fleshy on the dorsal and
+lateral surfaces of the mandible immediately anterior to the articulating
+surface. This muscle also has extensive insertion on the medial side of the
+lower mandible dorsal to the insertion of <i>M. pterygoideus dorsalis medialis</i> and
+posterior to the origin of <i>M. pseudotemporalis profundus</i> (figs. <a href="#figs1-2">1</a>, <a href="#figs3-4">3</a>, <a href="#figs5-8">5</a>, <a href="#figs17-18">17</a>,
+<a href="#figs17-18">18</a>, <a href="#figs19-20">19</a> and <a href="#figs19-20">20</a>).</p>
+
+<p>The fibers of <i>M. pseudotemporalis profundus</i> can be distinguished from
+the fibers of <i>M. adductor mandibulae posterior</i> because the pterygoideus nerve
+passes between the two (Lakjar, 1926:55). Rooth (1953:255-256) considers
+as part of this muscle the ventral aponeurosis of <i>pars profundus</i> of <i>M. adductor
+mandibulae externus</i> and all the fibers ventral to it. But I could not justify
+the inclusion of that aponeurosis as part of <i>M. adductor mandibulae posterior</i>
+in the doves because none of the fibers of <i>M. adductor mandibulae posterior</i>
+as I have described it were attached to that particular aponeurosis.</p>
+
+<p><b><i>M. protractor quadrati.</i></b>&mdash;The origin is fleshy from the posterior wall of
+the orbit medial to the foramen of the trigeminal nerve and also medial to the
+origin of <i>M. pseudotemporalis superficialis</i>. The origin describes an arc in
+the horizontal plane until it reaches the interorbital septum and the optic
+nerve. The insertion is fleshy on the posteromedial edge of the body of the
+quadrate and the orbital process of the quadrate and on the otic process of
+the quadrate. The muscle also inserts on the ventromedial surface of the
+orbital process of the quadrate and the adjacent area of the body of the
+quadrate (figs. <a href="#figs5-8">5</a>, <a href="#figs5-8">7</a>, <a href="#figs9-10">9</a>, <a href="#figs11-12">11</a>, <a href="#figs13-14">13</a>-<a href="#figs17-18">18</a>).</p>
+
+<p><i>M. protractor quadrati</i> possesses many fibers that arise from <i>M. protractor
+pterygoidei</i>. Consequently, it is difficult to determine the exact extent of the
+origin or the insertion of either muscle.</p>
+
+
+<h2>ACTION OF JAW MUSCLES</h2>
+
+<p><b><i>M. pterygoideus ventralis.</i></b>&mdash;Contraction of this muscle retracts the upper
+mandible by moving the palatine posteriorly, and simultaneously adducts the
+lower mandible.</p>
+
+<p><b><i>M. pterygoideus dorsalis.</i></b>&mdash;This muscle functions in essentially the same
+manner as <i>M. pterygoideus ventralis</i>. The result of having a part of its origin
+on the pterygoid as well as on the palatine is to facilitate retraction of the
+upper mandible.<span class="pagenum"><a name="Page_530" id="Page_530">[Pg 530]</a></span></p>
+
+<p><b><i>M. adductor mandibulae.</i></b>&mdash;This is the chief adductor of the lower mandible
+and the muscle functions solely in that capacity. In birds having great
+crushing ability, this muscle is much larger and more powerful and the skull
+is reinforced behind the quadrate in order to withstand the pressure of the
+lower mandible against the quadrate during adduction (Sims, 1955:374 and
+Bowman, 1961:219-222).</p>
+
+<p><b><i>M. pseudotemporalis profundus.</i></b>&mdash;With origin and insertion on highly
+movable bones, this muscle, when it contracts, retracts the upper mandible
+and adducts the lower mandible. Like the pterygoid muscles, this muscle,
+by itself, would allow the bird to grasp objects by means of its mandibles.
+However, <i>M. pseudotemporalis profundus</i> could produce a more powerful grip
+because it takes origin farther anteriorly on the lower mandible.</p>
+
+<p><b><i>M. protractor pterygoidei.</i></b>&mdash;Contraction of <i>M. protractor pterygoidei</i> pulls
+the pterygoid anteromedially and causes it to slide forward along the sphenoidal
+rostrum. This action aids in protraction of the upper mandible.</p>
+
+<p><b><i>M. depressor mandibulae.</i></b>&mdash;The depressor of the lower mandible is the
+sole muscle other than <i>M. geniohyoideus</i> involved in the function of abducting
+the lower jaw of doves. Its size can be correlated especially well with feeding
+habits of the bird. Other birds that force their closed mandibles into fruit,
+wood or the earth and then forcibly open them, belong to groups possessing
+enlarged depressors. Contraction of the muscle pulls the postarticular (retroarticular)
+process upward with the resultant downward movement of that
+part of the mandible which is anterior to the articulation. Since there is no
+"gaping" in doves the muscle is only large enough to overcome the inherent
+tone of the relaxed adductor muscles.</p>
+
+<p>In some non-passerine species as well as in certain passerines the muscle
+also serves to raise the upper jaw by acting on the quadrate, which is capable
+of rotating vertically on its otic process. Especially in the gapers, where
+resistance is offered near the tip of the lower mandible, contraction of the
+muscle pulls the entire mandible dorsad thus forcing the jugal and palatal struts
+forward (Zusi, 1959:537-539). The action supplements that of <i>Mm. protractor
+pterygoidei et quadrati</i> and is enhanced by anterior migration of the
+origin of <i>M. depressor mandibulae</i>.</p>
+
+<p>There is no lifting action involved in contraction of the depressor muscle
+in doves for two reasons&mdash;(A) the origin of the muscle is situated much too
+far posteriorly on the skull, and, more important, (B) the quadrate is not
+hinged for vertical movement. As will be discussed later, it moves only in
+a horizontal plane.</p>
+
+<p><b><i>M. pseudotemporalis superficialis.</i></b>&mdash;Like <i>M. adductor mandibulae</i>, this
+muscle performs only the one function of adducting the lower mandible, and
+like <i>M. pseudotemporalis profundus</i> it is a synergist of that muscle.</p>
+
+<p><b><i>M. adductor mandibulae posterior.</i></b>&mdash;Although this muscle undoubtedly
+acts as an adductor of the lower mandible, I believe that, because of its disadvantageous
+insertion so near the articulation, its main function must be
+concerned with firming the mandible against the quadrate. This is to say
+that its function is partially that of a ligament.</p>
+
+<p><b><i>M. protractor quadrati.</i></b>&mdash;When <i>M. protractor quadrati</i> contracts, the quadrate
+bone is swung medially. This action, as mentioned previously, results in<span class="pagenum"><a name="Page_531" id="Page_531">[Pg 531]</a></span>
+protraction of the upper jaw, and, as a consequence, its action supplements the
+action of <i>M. protractor pterygoidei</i>.</p>
+
+
+<h2>CRANIAL OSTEOLOGY</h2>
+
+<p>The ability of most birds to protract the upper mandible, and
+the structure of the skull which enables them to do so are responsible
+for common reference to the skull as "kinetic" (Beecher, 1951a:412;
+Fisher, 1955:175). The movement is effected by muscular action
+on a series of movable bones that exert their forward force on the
+upper mandible, which in turn swings on a horizontal hinge, the
+"naso-frontal hinge," at the base of the beak. The bone initiating
+the movement is the quadrate, which is hinged posteriorly by its
+otic process and which ordinarily swings up or down depending
+on the muscle or muscles being contracted at any given moment.
+The upward swing of the quadrate pushes the jugal bar, which is
+attached to its lateral tip, along its longitudinal axis, in an anterodorsal
+direction, and the force is transferred to the upper mandible,
+which is thereby elevated. A synergetic mechanism is simultaneously
+initiated by the same bone&mdash;the quadrate. Since the quadrate
+body articulates with the pterygoid, the upward movement forces
+the pterygoid to slide along a ridge in the ventral midline of the
+cranium, the sphenoidal rostrum, thus pushing the palatine forward
+and exerting an upward push on the upper mandible.</p>
+
+<p>In the columbids the quadrate has a bifurcated otic process that
+functions as the hinge. The posterior tips of the forks are situated
+almost vertically (one above the other) and the movement of the
+quadrate is not so much up and down, or vertical, as it is horizontal
+(fig. 12). When the quadrate moves medially the upper mandible
+is protracted; a lateral movement results in retraction. There is a
+slight, almost negligible, upward movement of the quadrate. The
+movements of the various bony elements were observed on a skull
+that had been made flexible by boiling in water for a minute as
+suggested by Beecher (1951a:412).</p>
+
+<p>Also in the columbids the naso-frontal hinge is not constructed
+in the same manner as it is in many other birds as there is not a
+simple hinge across the entire base of the beak. In fact, there is
+no true hinge at all in the area of the nasals, but those bones are
+extremely thin and they bend or flex under pressure. Actually,
+the hinge is double or divided. One part is on either side of the
+nasals. The hinges are situated at the posterodorsal tips of two
+thin processes of the maxillary bones and the appearance is not
+unlike that of half a span of a suspension bridge having the hinges<span class="pagenum"><a name="Page_532" id="Page_532">[Pg 532]</a></span>
+at the tops of the towers. Several other species of birds share
+this type of hinge construction with columbids.</p>
+
+<p>The movement of the lower jaw is, of course, the primary operation
+involved in opening the mouth. The lower jaw possesses a
+deep fossa at its posterior end, or on its posterodorsal surface,
+which articulates with the body of the quadrate bone. The length
+of that part of the mandible extending behind the articulation is
+directly correlated with the resistance offered the mandible in
+opening, since it is on the posterior extension that the depressor
+of the lower mandible inserts. The larger the muscle the more
+surface is needed for attachment. Also the added length of the
+mandible posterior to the articulation serves as a lever in opening
+the mandible, and the fulcrum is moved relatively farther forward.</p>
+
+<p>In birds lacking resistance to abduction of the lower mandible, as
+in doves, it is nevertheless necessary for a slight postarticular
+process to remain for the insertion of a small depressor muscle
+which, as mentioned previously, is necessary to counteract the relaxed
+adductor muscles of the lower jaw.</p>
+
+<p>There are many exceptions to the rule that birds have kinetic
+skulls, and usually a secondary fusion and reinforcement of bones
+around the hinge has limited or eliminated all movement. Sims
+(1955) describes the Hawfinch's immobile upper jaw, which is
+used as a powerful press in cracking the stones of fresh fruit.
+Skulls of woodpeckers have been modified somewhat in the same
+manner as a result of their foraging and nesting habits (Burt, 1930).</p>
+
+<p>The two most distantly related members of the genera under
+investigation are the White-winged Dove, <i>Zenaida asiatica</i>, and the
+Mourning Dove, <i>Zenaidura macroura</i>. They were chosen to demonstrate
+differences and likenesses in proportions of members of the
+genera.</p>
+
+<p>Ten measurements were taken on each skull, but simple observation
+reveals that, in relation to total length of the skull, the beak of
+the White-winged Dove is longer than that of the Mourning Dove.
+Tip of upper mandible to base of beak averaged 48.6 and 42.9
+per cent of the total length of the skull in the White-winged Dove
+and Mourning Dove, respectively. The position of the jugal bar
+has remained about the same with respect to the cranial part of
+the skull, and the entire cranial part of the skull is almost the same
+shape in the species studied.</p>
+
+<p>Likewise, in the White-winged Dove the distance from the
+anterior tip of the lower mandible to the anterior part of <i>M. adductor<span class="pagenum"><a name="Page_533" id="Page_533">[Pg 533]</a></span>
+mandibulae externus</i> is relatively longer in relation to the length
+of the lower mandible than in the Mourning Dove. Finally, the
+position of the jugal with respect to the naso-frontal hinge is about
+the same in the two species.</p>
+
+<p>Measurements and calculations indicate that the longer beak of
+the White-winged Dove as compared with the Mourning Dove is
+a function of the beak itself, not of differences in other parts of the
+skull. Measurements of skulls of Eared and Zenaida doves support
+this view.</p>
+
+
+<h2>OTHER MORPHOLOGICAL FEATURES</h2>
+
+<p>In the species dissected, the only variable muscle that I consider
+significant in revealing relationships is <i>M. pseudotemporalis profundus</i>.
+It is markedly enlarged in the White-winged Dove in
+relation to the homologous muscle in the Mourning Dove. The
+muscle is enlarged in such a manner that a lateral expansion of its
+mass is apparent in superficial or dorsal view (compare figures 15
+and 16). This, of course, indicates a muscle with powerful contraction,
+which has been unable to enlarge its circumference symmetrically
+because the eye is immediately dorsal to the muscle.
+Therefore it has expanded laterally. Ventral expansion is blocked
+by the presence of other muscles, and medially there is no surface
+for the insertion of additional fibers on the orbital process of the
+quadrate.</p>
+
+<p>The jaw musculature has been known for some time to be highly
+adaptive (Beecher, 1951a and b, 1953; Bowman, 1961; Burt, 1930;
+Engels, 1940 and Goodman and Fisher, 1962) and it would not be
+unreasonable, I think, to expect the jaw muscles of closely related
+species with similar habits to be similar. The beak of the White-winged
+Dove is longer in proportion to the length and height of
+the skull (exclusive of the beak) than is the beak of the Mourning
+Dove. The lengthened beak is probably an adaptation for nectar-feeding,
+which has been documented by McGregor, Alcorn and
+Olin (1962:263-264) while investigating pollinating agents of the
+Saguaro Cactus (<i>Cereus giganteus</i>), and by Gilman (1911:53)
+who observed the birds thrusting their bills into the flowers of the
+plant. Gilman indicated, however, that he could not be sure if
+the birds were seeking insects, pollen, or nectar. In any event
+the lengthened bill probably facilitates getting food by birds that
+probe parts of flowers. Hensley (1954:202) noted that both
+Mourning and White-winged doves were "exceptionally fond of<span class="pagenum"><a name="Page_534" id="Page_534">[Pg 534]</a></span>
+this source of nourishment." But he also points out an "interesting
+correlation" between the presence of the white-wings in the desert
+and the flowering of the saguaro. During his studies the appearance
+of the first white-wing preceded the opening of the first
+saguaro flower by two days. The flowering and fruiting season
+lasted until August, the month of termination of the white-wing
+breeding season.</p>
+
+<p>Since Hensley makes the correlation solely with the white-wings,
+I assume that there is no other obvious correlation between plants
+and birds among the remainder of the avifauna of the desert.
+Probably the Mourning Dove has failed to adapt to nectar-feeding
+as yet, and the White-winged Dove is the primary exploiter of this
+food niche. It should be noted, also, that the head of the Mourning
+Dove is smaller than the white-wing's, and perhaps there is no
+need for an elongated beak for reaching deeply into the flowers.</p>
+
+<p>The lengthened bill should produce no difficulties in protraction
+of the upper mandible and depression of the lower for the reason
+that in the dove there is no known resistance offered to these movements.
+The genus <i>Icterus</i> furnishes an example wherein resistance
+is met in the process of opening the mandibles; individuals of this
+genus thrust their closed bill into certain fruits and forcibly open
+their mandibles against the resistance of the pulp by strong protraction
+and depression, thus permitting the juices of the fruit to
+lake and ultimately to be consumed (Beecher, 1950:53). Beecher
+refers to the technique used in fruit-eating as "gaping." The result
+of gaping in <i>Icterus</i> should be the presence of a more massive set
+of muscles concerned with protraction and depression than is
+found in non-gaping groups. Beecher found the situation to be
+exactly as expected in that genus and in other genera which also
+gape. Meadowlarks (<i>Sturnella</i>) and caciques (<i>Archiplanus</i>) gape
+and pry in soil and wood respectively (Beecher, 1951a:422 and 426).</p>
+
+<p>The lengthened beak would be a problem when the White-winged
+Dove attempted to pick up objects such as seeds, which
+do in fact constitute the largest percentage of its diet in spite of its
+nectar-feeding habit. A similar situation exists in the genus <i>Icterus</i>,
+which is primarily adapted for gaping even though it shows a
+preference for insects when they are abundant (Beecher, 1950:53).
+The lengthened beak could be compensated for by (A) migration
+of the anterior end of the jugal bar toward the rostral tip of the
+bill and away from the fronto-nasal hinge with a simultaneous
+enlargement of the adductor muscles of the lower mandible, or<span class="pagenum"><a name="Page_535" id="Page_535">[Pg 535]</a></span>
+(B) enlargement of the one muscle that functions simultaneously
+as an efficient retractor of the upper mandible and adductor of the
+lower mandible, namely <i>M. pseudotemporalis profundus</i>. <i>Mm.
+pterygoideus dorsalis et lateralis</i> perform the same function, but
+because of their position on the lower mandible they, apparently,
+are stronger retractors of the upper mandible than they are adductors
+of the lower.</p>
+
+<p>It will be recalled that the jugal bar bears the same, or nearly
+the same, relationship to the cranium in the white-wing as it does
+in the Mourning Dove and that the heads, excluding the beaks of
+both species, are of nearly the same proportions. Also, <i>Mm. adductor
+mandibulae externus</i> and <i>pseudotemporalis superficialis</i>, the
+chief adductor muscles of the lower mandible, were not noticeably
+enlarged in the white-wing. It is also important to note that other
+combinations of migration of bone and/or enlargement of muscles
+could successfully solve the problem of providing sufficient leverage
+for the proper functioning of the lengthened mandibles, but
+it is my thesis that the second alternative sufficed for seed-eating
+habits and that that is the adaptation that was established; it is,
+in fact, the only one present in the White-winged Dove.</p>
+
+<p>It is unlikely that this enlarged muscle and beak are the remains
+of another series of jaw muscles that have converged toward the
+condition in Mourning Doves. Columbids are almost unquestionably
+monophyletic, and two lines would have had to diverge and
+then converge. There is no evidence for such an evolutionary
+occurrence.</p>
+
+
+<h2>GENERIC RELATIONSHIP</h2>
+
+<p>An attempt will be made here to summarize all the available
+evidence, direct or indirect, which bears on the problem of relationship
+of these genera. The original dissections which are discussed
+in this report are only valuable as one more bit of evidence concerning
+one characteristic that aids in clarification of generic relationship,
+and it is only in conjunction with other evidence that any
+satisfactory conclusion may be forthcoming.</p>
+
+
+<h3>Morphology</h3>
+
+<p>My dissections demonstrated that, in relation to the size of the
+doves, the jaw musculature of all the specimens investigated was
+so nearly alike that only one major difference was detected. <i>M.
+pseudotemporalis profundus</i> appeared to be enlarged in the White-winged
+Dove. This might have been predicted, since the white-wing<span class="pagenum"><a name="Page_536" id="Page_536">[Pg 536]</a></span>
+was also shown to possess an elongated beak, presumably an
+adaptation for nectar-feeding, which would necessitate additional
+muscle development in order to compensate for the added length.
+Measurements recorded from several skulls indicated that the
+heads of the birds (excluding the beak) are nearly proportional.</p>
+
+<p>Perhaps plumage patterns are the most widely used characters
+for determining generic relationships of birds. Ridgway (1916:339-385)
+followed the columbid classification of Salvadori (1893)
+using plumage patterns and body proportions to distinguish between
+the genera. In the genus <i>Zenaidura</i> he included the unique
+specimen <i>Zenaidura yucatanensis</i>, and he placed <i>auriculata</i> in
+<i>Zenaida</i>. The White-winged Dove was referred to a separate genus,
+<i>Melopelia</i>. He described the genus <i>Zenaidura</i> in the following
+manner:</p>
+
+<div class="blockquot"><p>"Plumage of head, neck and under parts soft and blended; bare orbital
+space moderate, broadest beneath eyes. Coloration plain, the proximal secondaries
+(sometimes adjacent wing-coverts and scapulars also) spotted with
+black; rectrices (except middle pair) with a black band across postmedian
+portion, the apical portion paler gray than basal portion, sometimes white; a
+small black subauricular spot; adult males with head, neck and anterior under
+parts more or less vinaceous and sides of neck glossed with metallic purple."</p></div>
+
+<p>He noted that the plumage of <i>Zenaida</i> was almost precisely as
+described for <i>Zenaidura</i>. Also, although all members of <i>Zenaida</i>
+reputedly possessed twelve rectrices, a characteristic of the genus,
+it was later found that <i>auriculata</i> possessed fourteen rectrices. The
+species was promptly placed in the genus <i>Zenaidura</i> by Peters
+(1934:213-215). In plumage and coloration, <i>Melopia</i> was described
+as similar to <i>Zenaida</i> and <i>Zenaidura</i> but without black spots on the
+wings.</p>
+
+<p>The White-winged Dove also has twelve rectrices, but Bond
+(1940:53) and Goodwin (1958:330-334) considered the number
+and shape of rectrices to be of minor importance when compared
+to the homologous markings of the plumage. Goodwin stated that
+his conclusion was emphasized by the fact that the tail of <i>auriculata</i>
+is intermediate in length and shape between those of <i>macroura</i> and
+<i>aurita</i>. In summary Goodwin "lumped" the genera <i>Zenaida</i> and
+<i>Zenaidura</i> under the genus <i>Zenaida</i>.</p>
+
+
+<h3>Nidification</h3>
+
+<p>It has been adequately documented that members of these
+genera closely resemble one another in their nesting and egg-laying
+habits. Bent (1932:407, 417), Davie (1889:157), Goss (1891:242)<span class="pagenum"><a name="Page_537" id="Page_537">[Pg 537]</a></span>
+and Nice (1922:466) have described the two, white eggs of the
+clutch of the Mourning Dove. They have also noted that their
+nests are composed mainly of twigs and may be constructed in
+trees, shrubs or on the ground. The Eared Dove has nearly identical
+habits (Bond, 1961:104), and a similar situation exists with the
+Zenaida Dove (Audubon, 1834:356; Bent, 1932:418-419).</p>
+
+<p>Like the other species, White-winged Doves lay two white or
+buffy eggs per clutch and build frail nests of sticks (Bent, 1932:431;
+Wetmore, 1920:141; Baird, Brewer and Ridgway, 1905:377).</p>
+
+<p>The point to be made here is simply this: If the species in
+question are to be considered congeneric then it might reasonably
+be expected that they would display some similarity in nidification
+and egg-laying. If their habits varied considerably it would not
+necessarily mean that their relationship was more distant, but
+similarities can usually be considered indicative of affinities because
+they are the phenotypic expression of the partially unaltered genotype
+of the common ancestor.</p>
+
+
+<h3>Interbreeding</h3>
+
+<p>Intergeneric crosses of columbids in captivity are common, but
+in nature there is little evidence that even interspecific crosses
+occur. Only one apparent hybrid between members of the genus
+<i>Zenaida</i> and genus <i>Zenaidura</i> has ever been discovered. The individual
+was taken on the Yucatan peninsula of Mexico, and was described
+and named as a new species (<i>Zenaidura yucatanensis</i>).</p>
+
+<p>Salvadori (1893:373), Ridgway (1916:353) and Peters (1934:213-215)
+agree that <i>Zenaidura yucatanensis</i> Lawrence is a hybrid
+between <i>Zenaidura macroura marginella</i> and <i>Zenaida aurita yucatanensis</i>.
+Ridgway (1916:355), however, notes that "... If <i>Zenaidura
+yucatanensis</i> Lawrence should prove to be really a distinct
+species, and not a hybrid ... unquestionably <i>Zenaida</i> and
+<i>Zenaidura</i> can not be separated generically, since the former is in
+every way exactly intermediate between the two groups." In the
+event that the unique type is a hybrid, the very fact of its existence
+supports the hypothesis that the genera are more closely related
+than is currently recognized.</p>
+
+
+<h3>Serology</h3>
+
+<p>There have been no investigations having as their sole purpose
+the clarification of the relationship of the genera <i>Zenaida</i> and <i>Zenaidura</i>.
+But some work has involved the comparison of the antigenic
+content of individual columbids with the antigenic content
+of a member of another species of the same family.<span class="pagenum"><a name="Page_538" id="Page_538">[Pg 538]</a></span></p>
+
+<p>Irwin and Miller (1961) tested, along with other columbids,
+members of <i>Zenaida</i> and <i>Zenaidura</i> for presence of, 1) species-specific
+antigens of <i>Columba guinea</i> (in relation to <i>Columba livia</i>)
+which are designated A, B, C and E, and, 2) species-specific antigens
+of <i>C. livia</i> (in relation to <i>C. guinea</i>) which are designated
+A&acute;, B&acute;, C&acute; and E&acute;.</p>
+
+<p>In the first test all five species of <i>Zenaida</i> and <i>Zenaidura</i> possessed
+antigens A and C, and all but <i>auriculata</i> possessed E. None of the
+species gave evidence of the presence of the B antigen of <i>C. guinea</i>
+in their blood. In the latter test only <i>macroura</i> had A&acute;, only <i>asiatica</i>
+had B&acute; (<i>aurita</i> was not tested for B&acute;), and none had C&acute; or E&acute;.</p>
+
+<p>These results would indicate that the five species are similar
+regarding antigenic content of the blood, and the variation is not
+consistent within one or the other genus as presently known.</p>
+
+
+<h2>SUMMARY AND CONCLUSION</h2>
+
+<p>The avian genus <i>Zenaida</i> is currently considered to be distinct
+from the genus <i>Zenaidura</i> by most columbid taxonomists. The jaw
+muscles of six Mourning Doves (<i>Zenaidura</i>) and five White-winged
+Doves (<i>Zenaida</i>) were investigated as to differences and similarities
+that might clarify the relationships of the genera. The sizes and
+proportions of skulls were also considered in 37 Mourning and
+White-winged doves and two Eared Doves. Larger size of <i>M.
+pseudotemporalis profundus</i>, the muscle that functions simultaneously
+as an adductor of the lower jaw and retractor of the upper
+jaw, in the White-winged Dove was the character found in the jaw
+musculature that could be used to support the contention that
+<i>Zenaidura</i> and <i>Zenaida</i> represent distinct genera. Larger size of
+this muscle in the white-wing seems to be related to its elongated
+beak. The long beak apparently is used for nectar-feeding in
+flowers of the Saguaro Cactus.</p>
+
+<p>Excluding the beak, skulls of the white-wing and Mourning
+doves are of nearly the same shape. Previous investigators have
+shown that in <i>Zenaida</i> and <i>Zenaidura</i> plumage patterns are similar,
+nesting habits and eggs are nearly identical, blood proteins are
+similar, and one "intergeneric" hybridization in nature is known.</p>
+
+<p>Consequently, it is concluded that species of the two alleged
+genera are congeneric, and I agree with Goodwin (1958) that the
+genus <i>Zenaida</i> (Bonaparte, 1838:41) should include the Mourning
+Dove, Eared Dove, Socorro Dove, Zenaida Dove, and White-winged<span class="pagenum"><a name="Page_539" id="Page_539">[Pg 539]</a></span>
+Dove. Their Latin binomina are <i>Zenaida macroura</i>, <i>Zenaida auriculata</i>,
+<i>Zenaida graysoni</i>, <i>Zenaida aurita</i>, and <i>Zenaida asiatica</i>, respectively.</p>
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="figs1-2" id="figs1-2"></a>
+<img src="images/image001.png" width="600" height="586" alt="Fig. 1. Medial view of left ramus of lower mandible of Mourning Dove. &times; 2-1/2.
+
+Fig. 2. Lateral view of right ramus of lower mandible of Mourning Dove. &times; 2-1/2." title="Fig. 1. Medial view of left ramus of lower mandible of Mourning Dove. &times; 2-1/2.
+
+Fig. 2. Lateral view of right ramus of lower mandible of Mourning Dove. &times; 2-1/2." />
+<span class="caption">Fig. 1. Medial view of left ramus of lower mandible of Mourning Dove. &times; 2-1/2.<br /><br />
+
+Fig. 2. Lateral view of right ramus of lower mandible of Mourning Dove. &times; 2-1/2.</span>
+</div><p><span class="pagenum"><a name="Page_540" id="Page_540">[Pg 540]</a></span></p>
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="figs3-4" id="figs3-4"></a>
+<img src="images/image002.png" width="600" height="793" alt="Fig. 3. Dorsal view of lower mandible of Mourning Dove. &times; 2-1/2.
+
+Fig. 4. Ventral view of lower mandible of Mourning Dove. &times; 2-1/2." title="Fig. 3. Dorsal view of lower mandible of Mourning Dove. &times; 2-1/2.
+
+Fig. 4. Ventral view of lower mandible of Mourning Dove. &times; 2-1/2." />
+<span class="caption">Fig. 3. Dorsal view of lower mandible of Mourning Dove. &times; 2-1/2.<br /><br />
+
+Fig. 4. Ventral view of lower mandible of Mourning Dove. &times; 2-1/2.</span>
+</div><p><span class="pagenum"><a name="Page_541" id="Page_541">[Pg 541]</a></span></p>
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="figs5-8" id="figs5-8"></a>
+<img src="images/image003.png" width="600" height="736" alt="Fig. 5. Dorsal view of right quadrate of Mourning Dove. &times; 5.
+
+Fig. 6. Dorsal view of right pterygoid of Mourning Dove. &times; 5.
+
+Fig. 7. Ventral view of right quadrate of Mourning Dove. &times; 5.
+
+Fig. 8. Ventral view of right pterygoid of Mourning Dove. &times; 5." title="Fig. 5. Dorsal view of right quadrate of Mourning Dove. &times; 5.
+
+Fig. 6. Dorsal view of right pterygoid of Mourning Dove. &times; 5.
+
+Fig. 7. Ventral view of right quadrate of Mourning Dove. &times; 5.
+
+Fig. 8. Ventral view of right pterygoid of Mourning Dove. &times; 5." />
+<span class="caption">Fig. 5. Dorsal view of right quadrate of Mourning Dove. &times; 5.<br /><br />
+
+Fig. 6. Dorsal view of right pterygoid of Mourning Dove. &times; 5.<br /><br />
+
+Fig. 7. Ventral view of right quadrate of Mourning Dove. &times; 5.<br /><br />
+
+Fig. 8. Ventral view of right pterygoid of Mourning Dove. &times; 5.</span>
+</div><p><span class="pagenum"><a name="Page_542" id="Page_542">[Pg 542]</a></span></p>
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="figs9-10" id="figs9-10"></a>
+<img src="images/image004.png" width="600" height="961" alt="Fig. 9. Right lateral view of skull of Mourning Dove. &times; 2-1/2.
+
+Fig. 10. Ventral view of skull of Mourning Dove. &times; 2-1/2." title="Fig. 9. Right lateral view of skull of Mourning Dove. &times; 2-1/2.
+
+Fig. 10. Ventral view of skull of Mourning Dove. &times; 2-1/2." />
+<span class="caption">Fig. 9. Right lateral view of skull of Mourning Dove. &times; 2-1/2.<br /><br />
+
+Fig. 10. Ventral view of skull of Mourning Dove. &times; 2-1/2.</span>
+</div><p><span class="pagenum"><a name="Page_543" id="Page_543">[Pg 543]</a></span></p>
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="figs11-12" id="figs11-12"></a>
+<img src="images/image005.png" width="600" height="894" alt="Fig. 11. Cross section of skull of Mourning Dove; anterior
+view. &times; 2-1/2.
+
+Fig. 12. Dorsal view of right quadrate of Mourning Dove
+showing movement which protracts the upper mandible
+(broken line). &times; 5." title="Fig. 11. Cross section of skull of Mourning Dove; anterior
+view. &times; 2-1/2.
+
+Fig. 12. Dorsal view of right quadrate of Mourning Dove
+showing movement which protracts the upper mandible
+(broken line). &times; 5." />
+<span class="caption">Fig. 11. Cross section of skull of Mourning Dove; anterior
+view. &times; 2-1/2.<br /><br />
+
+Fig. 12. Dorsal view of right quadrate of Mourning Dove
+showing movement which protracts the upper mandible
+(broken line). &times; 5.</span>
+</div><p><span class="pagenum"><a name="Page_544" id="Page_544">[Pg 544]</a></span></p>
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="figs13-14" id="figs13-14"></a>
+<img src="images/image006.png" width="600" height="822" alt="Fig. 13. Right lateral view of the jaw musculature of the White-winged Dove;
+superficial layer, &times; 5.
+
+Fig. 14. Right lateral view of the jaw musculature of the Mourning Dove;
+superficial layer. &times; 5." title="Fig. 13. Right lateral view of the jaw musculature of the White-winged Dove;
+superficial layer, &times; 5.
+
+Fig. 14. Right lateral view of the jaw musculature of the Mourning Dove;
+superficial layer. &times; 5." />
+<span class="caption">Fig. 13. Right lateral view of the jaw musculature of the White-winged Dove;
+superficial layer, &times; 5.<br /><br />
+
+Fig. 14. Right lateral view of the jaw musculature of the Mourning Dove;
+superficial layer. &times; 5.</span>
+</div><p><span class="pagenum"><a name="Page_545" id="Page_545">[Pg 545]</a></span></p>
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="figs15-16" id="figs15-16"></a>
+<img src="images/image007.png" width="600" height="750" alt="Fig. 15. Dorsal view of the jaw musculature of the White-winged Dove
+(right side); superficial layer. &times; 5.
+
+Fig. 16. Dorsal view of the jaw musculature of the Mourning Dove (right
+side); superficial layer. &times; 5." title="Fig. 15. Dorsal view of the jaw musculature of the White-winged Dove
+(right side); superficial layer. &times; 5.
+
+Fig. 16. Dorsal view of the jaw musculature of the Mourning Dove (right
+side); superficial layer. &times; 5." />
+<span class="caption">Fig. 15. Dorsal view of the jaw musculature of the White-winged Dove
+(right side); superficial layer. &times; 5.<br /><br />
+
+Fig. 16. Dorsal view of the jaw musculature of the Mourning Dove (right
+side); superficial layer. &times; 5.</span>
+</div><p><span class="pagenum"><a name="Page_546" id="Page_546">[Pg 546]</a></span></p>
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="figs17-18" id="figs17-18"></a>
+<img src="images/image008.png" width="600" height="714" alt="Fig. 17. Dorsal view of the jaw musculature of the White-winged Dove (right
+side); middle layer. &times; 5.
+
+Fig. 18. Dorsal view of the jaw musculature of the Mourning Dove (right
+side); middle layer. &times; 5." title="Fig. 17. Dorsal view of the jaw musculature of the White-winged Dove (right
+side); middle layer. &times; 5.
+
+Fig. 18. Dorsal view of the jaw musculature of the Mourning Dove (right
+side); middle layer. &times; 5." />
+<span class="caption">Fig. 17. Dorsal view of the jaw musculature of the White-winged Dove (right
+side); middle layer. &times; 5.<br /><br />
+
+Fig. 18. Dorsal view of the jaw musculature of the Mourning Dove (right
+side); middle layer. &times; 5.</span>
+</div><p><span class="pagenum"><a name="Page_547" id="Page_547">[Pg 547]</a></span></p>
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="figs19-20" id="figs19-20"></a>
+<img src="images/image009.png" width="600" height="727" alt="Fig. 19. Dorsal view of the jaw musculature of the White-winged Dove
+(right side); deep layer. &times; 5.
+
+Fig. 20. Dorsal view of the jaw musculature of the Morning Dove
+(right side); deep layer. &times; 5." title="Fig. 19. Dorsal view of the jaw musculature of the White-winged Dove
+(right side); deep layer. &times; 5.
+
+Fig. 20. Dorsal view of the jaw musculature of the Morning Dove
+(right side); deep layer. &times; 5." />
+<span class="caption">Fig. 19. Dorsal view of the jaw musculature of the White-winged Dove
+(right side); deep layer. &times; 5.<br /><br />
+
+Fig. 20. Dorsal view of the jaw musculature of the Morning Dove
+(right side); deep layer. &times; 5.</span>
+</div><p><span class="pagenum"><a name="Page_548" id="Page_548">[Pg 548]</a></span></p>
+<hr style="width: 65%;" />
+
+<div class="figcenter" style="width: 600px;">
+<a name="figs21-22" id="figs21-22"></a>
+<img src="images/image010.png" width="600" height="899" alt="Fig. 21. Ventral view of the jaw musculature of the White-winged Dove
+(M. depressor mandibulae not shown). &times; 5.
+
+Fig. 22. Ventral view of the jaw musculature of the Mourning Dove (M.
+depressor mandibulae not shown). &times; 5." title="Fig. 21. Ventral view of the jaw musculature of the White-winged Dove
+(M. depressor mandibulae not shown). &times; 5.
+
+Fig. 22. Ventral view of the jaw musculature of the Mourning Dove (M.
+depressor mandibulae not shown). &times; 5." />
+<span class="caption">Fig. 21. Ventral view of the jaw musculature of the White-winged Dove
+(M. depressor mandibulae not shown). &times; 5.<br /><br />
+
+Fig. 22. Ventral view of the jaw musculature of the Mourning Dove (M.
+depressor mandibulae not shown). &times; 5.</span>
+</div>
+
+
+
+<hr style="width: 65%;" /><p><span class="pagenum"><a name="Page_549" id="Page_549">[Pg 549]</a></span></p>
+<h2>LITERATURE CITED</h2>
+
+
+<p>
+<span class="smcap">Adams, L. A.</span><br />
+<span class="i4">1919. A memoir on the phylogeny of the jaw muscles in recent and fossil
+vertebrates. Annals New York Acad. Sci., 28:51-166.</span><br />
+<br />
+<span class="smcap">Audubon, J. J.</span><br />
+<span class="i4">1834. Ornithological biography. Vol. II. Adam &amp; Charles Black, Edinburgh,
+xxxii + 588 pp.</span><br />
+<br />
+<span class="smcap">Baird, S. F.</span>, <span class="smcap">Brewer, T. M.</span>, and <span class="smcap">Ridgway, R.</span><br />
+<span class="i4">1905. The land birds of North America. Little, Brown, and Company,
+Boston, 560 + xxvii pp.</span><br />
+<br />
+<span class="smcap">Beecher, W. J.</span><br />
+<span class="i4">1950. Convergent evolution in the American orioles. Wilson Bull. 62:51-86.</span><br />
+<span class="i4">1951a. Adaptations for food-getting in the American blackbirds. Auk,
+68:411-440.</span><br />
+<span class="i4">1951b. Convergence in the Coerebidae. Wilson Bull., 63:274-287.</span><br />
+<span class="i4">1953. A phylogeny of the oscines. Auk, 70:270-333.</span><br />
+<br />
+<span class="smcap">Bent, A. C.</span><br />
+<span class="i4">1932. Life histories of North American gallinaceous birds. Bull. U. S.
+Nat. Mus., 162:xi + 490 pp., 93 pls.</span><br />
+<br />
+<span class="smcap">Bonaparte, C. L.</span><br />
+<span class="i4">1838. Geographical and comparative list of the birds of Europe and
+North America. John Van Voorst, London, vii + 68 pp.</span><br />
+<br />
+<span class="smcap">Bond, J.</span><br />
+<span class="i4">1961. Birds of the West Indies. Houghton Mifflin Company, Boston. 256
+pp., 8 pls., 186 figs.</span><br />
+<br />
+<span class="smcap">Bowman, R. I.</span><br />
+<span class="i4">1961. Morphological differentiation and adaptation in the Galapagos
+finches. Univ. California Publ. Zool., 58:vii + 302 pp., 22 pls.,
+74 figs., 63 tables.</span><br />
+<br />
+<span class="smcap">Burt, W. H.</span><br />
+<span class="i4">1930. Adaptive modifications in the woodpeckers. Univ. California Publ.
+Zool., 32:455-524.</span><br />
+<br />
+<span class="smcap">Cain, A. J.</span><br />
+<span class="i4">1956. The genus in evolutionary taxonomy. Syst. Zool., 5:97-109.</span><br />
+<br />
+<span class="i4">1959. Taxonomic concepts. Ibis, 101:302-318.</span><br />
+<br />
+<span class="smcap">Davie, O.</span><br />
+<span class="i4">1889. Nests and eggs of North American birds. Hann &amp; Adair, Columbus,
+455 + xii pp., 13 pls.</span><br />
+<br />
+<span class="smcap">Edgeworth, F. H.</span><br />
+<span class="i4">1935. The cranial muscles of vertebrates. Cambridge Univ. Press, viii +
+493 pp., 841 figs.</span><br />
+<br />
+<span class="smcap">Engels, W. L.</span><br />
+<span class="i4">1940. Structural adaptations in thrashers (Mimidae: genus <i>Toxostoma</i>)
+with comments on interspecific relationships. Univ. California
+Publ. Zool., 42:341-400, 24 figs., 11 tables.</span><br />
+<br />
+<span class="smcap">Fisher, H. I.</span><br />
+<span class="i4">1955. Some aspects of the kinetics in the jaws of birds. Wilson Bull.,
+67:175-188, 4 figs., 6 tables.</span><br />
+<br />
+<span class="smcap">Gadow, H.</span><br />
+<span class="i4">1891. Vogel: I. Anatomischer Theil. Bronn's Klassen und Ordnungen des
+Thier-Reichs. C. F. Winter, Leipzig, 6:1-1,008, many figs., 59 pls.</span><br />
+<br />
+<span class="smcap">Gilman, M. F.</span><br />
+<span class="i4">1911. Doves on the Pima Reservation. Condor, 13:51-56.</span><br />
+<br />
+<span class="smcap">Goodman, D. C.</span>, and <span class="smcap">Fisher, H. I.</span><br />
+<span class="i4">1962. Functional anatomy of the feeding apparatus in waterfowl. Southern
+Illinois Univ. Press, Carbondale, xii + 193 pp.</span><br /><span class="pagenum"><a name="Page_550" id="Page_550">[Pg 550]</a></span>
+<br />
+<span class="smcap">Goodwin, D.</span><br />
+<span class="i4">1958. Remarks on the taxonomy of some American doves. Auk, 75:330-334.</span><br />
+<br />
+<span class="smcap">Goss, N. S.</span><br />
+<span class="i4">1891. History of the birds of Kansas. Geo. W. Crane &amp; Co., Topeka,
+692 pp., 35 pls.</span><br />
+<br />
+<span class="smcap">Hensley, M. M.</span><br />
+<span class="i4">1954. Ecological relations of the breeding bird populations of the desert
+biome of Arizona. Ecol. Monographs, 24:185-207.</span><br />
+<br />
+<span class="smcap">Hofer, H.</span><br />
+<span class="i4">1950. Zur Morphologie der Kiefermuskulatur der Vogel. Zool. Jahrb.
+Jena (Anat.), 70:427-556, 44 figs.</span><br />
+<br />
+<span class="smcap">Irwin, M. R.</span>, and <span class="smcap">Miller, W. J.</span><br />
+<span class="i4">1961. Interrelationships and evolutionary patterns of cellular antigens in
+columbidae. Evolution, 15:30-43.</span><br />
+<br />
+<span class="smcap">Jackson, A. S.</span><br />
+<span class="i4">1941. The mourning dove in Throckmorton County, Texas, Unpubl.
+manuscript (Abstract).</span><br />
+<br />
+<span class="smcap">Kiel, W. H., Jr.</span>, and <span class="smcap">Harris, J. T.</span><br />
+<span class="i4">1956. Status of the white-winged dove in Texas. Trans. 21st N. Amer.
+Wildl. Conf., pp. 376-388.</span><br />
+<br />
+<span class="smcap">Knappen. P.</span><br />
+<span class="i4">1938. Preliminary report on some of the important foods of the mourning
+dove in the southeastern U. S. Trans. 3rd N. Amer. Wildl. Conf.,
+pp. 776-781.</span><br />
+<br />
+<span class="smcap">Lakjer, T.</span><br />
+<span class="i4">1926. Studien Uber die Trigeminus-versorgte Kaumuskulatur der Sauropsiden.
+C. A. Reitzel Buchhandlung, Kopenhagen, 154 pp., 26 pls.</span><br />
+<br />
+<span class="smcap">Leopold, A. S.</span><br />
+<span class="i4">1943. Autumn feeding and flocking habits of the mourning dove in
+southern Missouri. Wilson Bull., 55:151-154.</span><br />
+<br />
+<span class="smcap">McGregor, S. E.</span>, <span class="smcap">Alcorn, S. M.</span>, and <span class="smcap">Olin, G.</span><br />
+<span class="i4">1962. Pollination and pollinating agents of the saguaro. Ecology, 43:259-267.</span><br />
+<br />
+<span class="smcap">Nice, M. M.</span><br />
+<span class="i4">1922. A study of the nesting of mourning doves. Auk, 39:457-474;
+40:37-58.</span><br />
+<br />
+<span class="smcap">Peters, J. L.</span><br />
+<span class="i4">1934. The classification of some American pigeons. Condor, 36:213-215.</span><br />
+<br />
+<span class="i4">1937. Check-list of birds of the world. Vol. III. Harvard Univ. Press,
+Cambridge, xiii + 311 pp.</span><br />
+<br />
+<span class="smcap">Rooth, J.</span><br />
+<span class="i4">1953. On the correlation between the jaw muscles and the structure of
+the skull in <i>Columba palumbus</i>. Kon. Ned. Akad. Wet.; Proc.
+Sect. Sci., Vol. LVI, serie C, pp. 251-264.</span><br />
+<br />
+<span class="smcap">Salvadori, T.</span><br />
+<span class="i4">1893. Catalogue of birds in the British Museum, 21:xvii + 676 pp., 15
+pls. + 17 pp.</span><br />
+<br />
+<span class="smcap">Shufeldt, R. W.</span><br />
+<span class="i4">1890. The myology of the raven. MacMillan &amp; Co., London, xix + 343
+pp., 76 figs.</span><br /><span class="pagenum"><a name="Page_551" id="Page_551">[Pg 551]</a></span>
+<br />
+<span class="smcap">Sims, R. W.</span><br />
+<span class="i4">1955. The morphology of the head of the hawfinch. Bull. Brit. Mus.
+(Nat. Hist.) Zool., 2:369-393.</span><br />
+<br />
+<span class="smcap">Wetmore, A.</span><br />
+<span class="i4">1920. Observations of the habits of the white-winged dove. Condor,
+22:140-146.</span><br />
+<br />
+<span class="smcap">Zusi, R. L.</span><br />
+<span class="i4">1959. The function of the depressor mandibulae muscle in certain passerine
+birds. Auk, 76:537-539.</span><br />
+</p>
+
+
+<p><i>Transmitted June 3, 1963.</i></p>
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
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+White-winged Doves, by Robert L. Merz
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+The Project Gutenberg EBook of Jaw Musculature of the Mourning and
+White-winged Doves, by Robert L. Merz
+
+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: Jaw Musculature of the Mourning and White-winged Doves
+
+Author: Robert L. Merz
+
+Release Date: April 17, 2010 [EBook #32018]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK JAW MUSCULATURE--DOVES ***
+
+
+
+
+Produced by Chris Curnow, Joseph Cooper, Diane Monico, and
+the Online Distributed Proofreading Team at
+https://www.pgdp.net
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+
+
+UNIVERSITY OF KANSAS PUBLICATIONS
+MUSEUM OF NATURAL HISTORY
+
+Volume 12, No. 12, pp. 521-551, 22 figs.
+October 25, 1963
+
+
+Jaw Musculature
+Of the Mourning and White-winged Doves
+
+
+BY
+
+ROBERT L. MERZ
+
+
+UNIVERSITY OF KANSAS
+LAWRENCE
+1963
+
+
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY
+
+Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
+Theodore H. Eaton, Jr.
+
+Volume 12, No. 12, pp. 521-551, 22 figs.
+Published October 25, 1963
+
+
+UNIVERSITY OF KANSAS
+Lawrence, Kansas
+
+
+PRINTED BY
+JEAN M. NEIBARGER, STATE PRINTER
+TOPEKA, KANSAS
+1963
+
+29-7865
+
+
+
+
+Jaw Musculature
+Of the Mourning and White-winged Doves
+
+BY
+
+ROBERT L. MERZ
+
+
+For some time many investigators have thought that the genus _Zenaida_,
+which includes the White-winged and Zenaida doves, and the genus
+_Zenaidura_, which includes the Mourning, Eared, and Socorro doves
+(Peters, 1937:83-88), are closely related, perhaps more closely than is
+indicated by separating the several species into two genera. It is the
+purpose of this paper to report investigations on the musculature of
+the jaw of doves with the hope that, together with the results of other
+studies, the relationships of the genera _Zenaida_ and _Zenaidura_ can
+be elucidated.
+
+
+METHODS AND MATERIALS
+
+In order to determine in each species the normal pattern of musculature
+of the jaws, heads of 13 specimens of doves were dissected (all
+material is in the Museum of Natural History of The University of
+Kansas): White-winged Doves (_Zenaida asiatica_), 40323, 40324, 40328,
+40392, 40393; Zenaida Doves (_Z. aurita_), 40399, 40400; Mourning Doves
+(_Zenaidura macroura_), 40326, 40394, 40395, 40396, 40397, 40398.
+
+Thirty-seven skulls from the collection of the Museum of Natural
+History of The University of Kansas and two skulls from the United
+States National Museum were measured. The measurements are on file in
+the Library of The University of Kansas in a dissertation deposited
+there by me in 1963 in partial fulfillment of requirements for the
+degree of Master of Arts in Zoology. Specimens used were: White-winged
+Doves, KU 19141, 19142, 19143, 19144, 19145, 19146, 19147, 23138,
+23139, 24337, 24339, 24341, 23592, 23593, 24340, 31025, 31276; Mourning
+Doves, KU 14018, 14781, 15347, 15533, 15547, 15550, 15662, 15778,
+15872, 16466, 17782, 17786, 17788, 17795, 19153, 19242, 20321, 21669,
+22394, 22715; Eared Doves (_Zenaidura auriculata_), USNM 227496,
+318381. Additionally, the skulls of the Zenaida Doves mentioned above
+were measured. All measurements were made with a dial caliper and read
+to tenths of a millimeter.
+
+
+ACKNOWLEDGMENTS
+
+My appreciation is extended to Professor Richard F. Johnston, who
+advised me during the course of this study, and to Professors A. Byron
+Leonard and Theodore H. Eaton for critically reading the manuscript.
+
+I would like also to acknowledge the assistance of Dr. Robert M. Mengel
+and Mr. Jon C. Barlow for suggestions on procedure, and Mr. William C.
+Stanley, who contributed specimens of Mourning Doves for study. Mr.
+Thomas H. Swearingen offered considerable advice on production of
+drawings and Professor E. Raymond Hall suggested the proper layout of
+the same and gave editorial assistance otherwise, as also did Professor
+Johnston.
+
+
+MYOLOGY
+
+The jaw musculature of doves is not an imposing system. The eating
+habits impose no considerable stress on the muscles; the mandibles are
+not used for crushing seeds, spearing, drilling, gaping, or probing as
+are the mandibles of many other kinds of birds. Doves use their
+mandibles to procure loose seeds and grains, which constitute the major
+part of their diet (Leopold, 1943; Kiel and Harris, 1956: 377; Knappen,
+1938; Jackson, 1941), and to gather twigs for construction of nests.
+Both activities require but limited gripping action of mandibles. The
+crushing habit of a bird such as the Hawfinch (_Coccothraustes
+coccothraustes_), on the other hand, involves extremely powerful
+gripping (see, for example, Sims, 1955); the contrast is apparent in
+the development of the jaw musculature in the two types. Consequently,
+it is not surprising to find a relatively weak muscle mass in the jaw
+of doves, and because the musculature is weak there are few pronounced
+osseous fossae, cristae and tubercles. As a result, the bones, in
+addition to being small in absolute size, are relatively weaker when
+compared to skulls of birds having more distinctive feeding habits
+which require more powerful musculature.
+
+The jaw muscles of the species dissected for this study are, in gross
+form, nearly identical from one species to another. Thus, a description
+of the pertinent myology of each species is unnecessary; one basic
+description is hereby furnished, with remarks on the variability
+observed between the species.
+
+The terminology adopted by me for the jaw musculature is in boldfaced
+italic type. Synonyms are in italic type and are the names most often
+used by several other writers.
+
+ ~_M. pterygoideus ventralis:_~ part of Mm. pterygoidei, Gadow,
+ 1891:323-325, table 26, figs. 1, 2, 3 and 4, and table 27,
+ fig. 3--part of M. pterygoideus internus, Shufeldt, 1890:20,
+ figs. 3, 5, 6, 7 and 11--part of M. adductor mandibulae
+ internus, Edgeworth, 1935:58, figs. 605c and 607--part of M.
+ pterygoideus anterior, Adams, 1919:101, pl. 8, figs. 2 and 3.
+
+ ~_M. pterygoideus dorsalis:_~ part of Mm. pterygoidei,
+ Gadow, 1891:323-325, table 26, fig. 7 and table 27, figs. 1
+ and 3--part of M. pterygoideus internus, Shufeldt,
+ 1890:20--part of M. adductor mandibulae internus, Edgeworth,
+ 1935:58, fig. 605c--? part of M. pterygoideus anterior,
+ Adams, 1919:101, pl. 8, figs. 2 and 3.
+
+ ~_M. adductor mandibulae externus:_~ _a_) ~_pars
+ superficialis:_~ parts 1 and 2 of M. temporalis, Gadow,
+ 1891:320-321--part of M. temporal, Shufeldt, 1890:16,
+ figs. 5 and 7--part of M. adductor mandibulae externus,
+ Edgeworth, 1935:58-60--M. capiti-mandibularis medius and
+ profundus, Adams, 1919:101, pl. 8, fig. 1.
+
+ _b_) ~_pars medialis:_~ ? parts 1, 2 and 3 of M. temporalis,
+ Gadow, 1891:320-322--part of M. masseter and ? part of M.
+ temporal, Shufeldt, 1890:16-18, figs. 5, 6, 7 and 11--part
+ of M. adductor mandibulae externus, Edgeworth,
+ 1935:58-60--M. capiti-mandibularis superficialis, first
+ part, Adams, 1919:100-101, pl. 8, fig. 1.
+
+ _c_) ~_pars profundus:_~ part 2 of M. temporalis, Gadow,
+ 1891:321, table 27, fig. 2--part of M. temporal and ? part
+ of M. masseter, Shufeldt, 1890:16-18--part of M. adductor
+ mandibulae externus, Edgeworth, 1935:58-60--? part of M.
+ capiti-mandibularis medius and all of pars superficialis,
+ second part, Adams, 1919:100-101.
+
+ ~_M. pseudotemporalis profundus:_~ M. quadrato-maxillaris,
+ Gadow, 1891:322-323--M. pterygoideus externus, Shufeldt,
+ 1890:20-21, figs. 3, 5 and 11--part of M. adductor mandibulae
+ medius, Edgeworth, 1935:58-59--? part of M. pterygoideus
+ posterior, Adams, 1919:101, pl. 8, figs. 2 and 3.
+
+ ~_M. protractor pterygoidei:_~ part 4b of M. temporalis,
+ Gadow, 1891: 322-323, table 27, fig. 4--part of M.
+ entotympanious, Shufeldt, 1890:19-20, figs. 3 and 11--part
+ of M. spheno-pterygo-quadratus, Edgeworth, 1935:57.
+
+ ~_M. depressor mandibulae:_~ M. digastricus s. depressor
+ mandibulae, Gadow, 1891:318-319--M. biventer maxillae,
+ Shufeldt, 1890:18-19, figs. 3, 4, 5, 6, 7 and 11.
+
+ ~_M. pseudotemporalis superficialis:_~ M. spheno-maxillaris,
+ Gadow, 1891:323--part of M. temporal, Shufeldt, 1890:16--part
+ of M. pseudotemporalis, Hofer, 1950:468-477--part of M.
+ adductor mandibulae medius, Edgeworth, 1935:277.
+
+ ~_M. adductor mandibulae posterior:_~ ? part of M. temporal,
+ Shufeldt, 1890:16--part of M. adductor mandibulae medius,
+ Edgeworth, 1935:58-59--? part of M. pterygoideus posterior,
+ Adams, 1919:101, pl. 8, figs. 2 and 3.
+
+ ~_M. protractor quadrati:_~ part 4a of M. temporalis, Gadow,
+ 1891:322-323, table 27, fig. 4--part of M. entotympanicus,
+ Shufeldt, 1890:19-20, figs. 3 and 11--part of M.
+ spheno-pterygo-quadratus, Edgeworth, 1935:57.
+
+The terminology adopted by me is that of Lakjar (1926) except that the
+divisions of _M. depressor mandibulae_ are designated by the Latinized
+equivalents of the names used by Rooth (1953:261-262).
+
+~_M. pterygoideus ventralis lateralis._~--The origin is fleshy and by
+aponeurosis on the ventral side of the palatine anterior to the
+palatine fossa. The insertion is fleshy on the ventromedial surface of
+the lower mandible and continues along the anteromedial surface of the
+internal angular process to its distal tip. A few fibers leave _pars
+lateralis_ and insert on an aponeurosis which receives also all the
+fibers of _M. pterygoideus dorsalis lateralis_. The latter fact may
+have prompted Rooth (1953:257) to make the statement that the fibers
+originating on the dorsal part of the palatine inserted more laterally
+than those originating on the ventral side. Rooth worked with _Columba
+palumbus_, the Woodpigeon, and his description concerned _M. adductor
+mandibulae internus pterygoideus_, which is composed of _Mm.
+pterygoideus ventralis et dorsalis_ of Lakjar (1926). His assertion
+that ventral fibers, that is to say, fibers arising on the ventral
+surface of the palatine, insert medially does not appear to be
+completely true for doves.
+
+Aponeuroses cover most of the lower surface of the muscle and one or
+two nerves extend into the substance of the muscle. The nerves run from
+the anterior edge of _M. pterygoideus dorsalis medialis_ and farther
+posteriorly from a separation in the muscle.
+
+~_M. pterygoideus ventralis medialis._~--The origin is by aponeurosis
+from the ventral surface of the palatine and fleshy from the palatine
+fossa. The aponeurosis is the same that gives origin to the fibers of
+_pars lateralis_. Part of the aponeurosis becomes tendonlike in the
+middle of _M. pterygoideus ventralis_ and separates its two divisions.
+The insertion is fleshy on the lower one-third of the anterior surface
+of the internal angular process of the lower mandible, and by two
+tendons on the distal tip of that process. Many of the fibers of _pars
+medialis_ insert on the tendons. The fibers at their insertion are not
+distinctly separate from those of _pars lateralis_ and there is
+considerable mingling of the fibers. Consequently, the medial part of
+_M. pterygoideus ventralis_ cannot be removed as a part distinct from
+the lateral part (figs. 1, 4, 10, 21 and 22).
+
+Ordinarily _M. pterygoideus ventralis_ does not cross the ventral edge
+of the lower mandible, but in one white-wing the muscle was slightly
+expanded on the right side and it could be seen in lateral view. The
+homologous muscle in _Columba palumbus_ apparently is consistently
+visible in lateral view. (See Rooth, 1953, fig. 6.)
+
+~_M. pterygoideus dorsalis medialis._~--The origin is fleshy on the
+dorsolateral surface of the palatine immediately anterior to the
+pterygoid and also on the anterior, dorsolateral, posterior and
+ventromedial surfaces of the pterygoid. The insertion is fleshy on the
+ventromedial surface of the lower mandible and the anterior surface of
+the internal angular process immediately dorsal to the insertion of _M.
+pterygoideus ventralis lateralis_.
+
+~_M. pterygoideus dorsalis lateralis._~--The origin is fleshy from the
+dorsolateral surface of the palatine, anterior to the origin of _pars
+medialis_ and the insertion is by means of an aponeurosis on the medial
+surface of the lower mandible, lateral to the insertion of _M.
+pterygoideus ventralis lateralis_. The aponeurosis crosses the medial
+side of the insertion of _M. pterygoideus dorsalis medialis_. The
+fibers run in a posteroventrolateral direction and insert on the
+ventromedial side of the aponeurosis (figs. 1, 6, 8, 9, 13-22).
+
+In one individual, a Mourning Dove, the origin of _pars lateralis_ of
+_M. pterygoideus dorsalis_ extended to the pterygoid. With this one
+exception the muscle was uniform throughout the several species.
+
+~_M. adductor mandibulae externus._~--This is the most complex muscle
+in the jaw owing to its system of tendons and aponeuroses. Three
+divisions of this muscle were described by Lakjar (1926:45-46) and the
+divisions appear to be distinguishable in the doves, but there is no
+clear line of demarcation for any of the parts and the following
+description is based upon my own attempts to delineate the muscle.
+
+~_M. adductor mandibulae externus superficialis._~--The origin is
+fleshy from the most lateral area of the temporal fossa. Dorsally the
+origin is bounded by the base of the postorbital process and ventrally
+by the temporal process. The fibers converge upon a tendon that passes
+beneath the postorbital ligament and runs anteriorly among the fibers
+of _pars profundus_. The insertion is tendinous on the dorsal surface
+of the lower mandible in common with the dorsal aponeurosis of _pars
+profundus_. The insertion is immediately anterior to the ventral
+aponeurosis of _pars profundus_ near the medial edge of the dorsal
+surface on a tubercle at the posterior end of the dorsal ridge of the
+lower mandible.
+
+~_M. adductor mandibulae externus medialis._~--The origin is by a flat,
+heavy tendon from the temporal process. The tendon is attached almost
+vertically on the temporal process. It twists approximately 130 deg. as
+it runs anteriorly, and becomes a thin aponeurosis, which gives rise on
+its dorsal and ventral surfaces to many fibers that insert in a
+fan-shaped area on the mandibular fossa. Fibers from the dorsal and
+dorsomedial sides of the heavy tendon run rostrad and insert on the
+ventral surface of the dorsal aponeurosis of _pars profundus_. From the
+ventral surface the most posterior fibers converge on an aponeurosis
+that inserts on a transverse crista on the dorsal surface of the
+mandible immediately lateral to the ventral aponeurosis of _pars
+profundus_ and dorsal to the insertion of ~_M. adductor mandibulae
+posterior_~. The more anterior fibers insert fleshily on the mandibular
+fossa. The tendon of origin is actually one with the ventral
+aponeurosis of _pars profundus_, which is situated in a horizontal
+plane. The insertion is primarily a fleshy attachment on the mandibular
+fossa. Some of the fibers that arise on the dorsomedial and lateral
+surfaces of the tendon of origin attach to another tendon, which
+inserts in the midline of the mandibular fossa on a small tubercle near
+the anterior end. Also, there is insertion by an aponeurosis anterior
+to _M. adductor mandibular posterior_ as stated above. Fibers attach to
+the dorsal and ventral side of the aponeurosis.
+
+~_M. adductor mandibulae externus profundus._~--The origin is fleshy
+from the medial surface of the temporal fossa, the posterior wall of
+the orbit and the otic process of the quadrate. The origin is bounded
+laterally by the origin of _pars superficialis_ and medially by the
+origin of _M. pseudotemporalis superficialis_. Ventrally the muscle
+lies against its own ventral aponeurosis, which originates on the
+posterior wall of the orbit immediately above the articulation of the
+otic process of the quadrate, and which also receives many fibers from
+the surface of the quadrate. The insertion is primarily by means of two
+aponeuroses. The most dorsal aponeurosis inserts on a tubercle at the
+posterior tip of the dorsal edge of the mandible. The lateral tendon of
+_M. pseudotemporalis superficialis_ converges with the aponeurosis. It
+is superficial and there are no fibers on its dorsal surface. The
+ventral aponeurosis inserts on a crista immediately below the insertion
+of the dorsal aponeurosis. It receives fibers on its ventral surface
+from the otic process of the quadrate, and on its dorsal surface gives
+rise to fibers that insert on the dorsal aponeurosis (figs. 2, 3, 5, 9,
+10, 11, 13-18).
+
+The tendon of insertion of _pars medialis_ of _M. adductor mandibulae
+externus_ does not become a superficial aponeurosis posteriorly in the
+Zenaida Dove as it does in the Mourning and White-winged doves.
+
+~_M. pseudotemporalis profundus._~--The origin is fleshy from the
+medial and partially from the dorsal surface of the lower mandible. The
+origin is almost completely anterior to and partly dorsal and ventral
+to the medial (most anterior) insertion of _M. pseudotemporalis
+superficialis_. The anterior margin of the origin is at the point where
+the mandibular ramus of the trigeminal nerve enters the mandible.
+Posteriorly the origin is bounded by the insertion of _M. adductor
+mandibulae posterior_, and ventrally by a ridge that is situated about
+halfway down the medial side of the mandible. The insertion is by
+aponeurosis on the tip of the orbital process of the quadrate and
+fleshily on the anterior surface of the same process. The aponeurosis
+extends about three-fifths of the distance along the muscle and it is
+dorsal or superficial to all of the fibers. Many fibers insert on the
+ventral side of the aponeurosis (figs. 1, 5, 13, 14, 15, 16, 21 and
+22).
+
+This muscle is the most variable of all the jaw muscles. In the
+Mourning Dove the muscle appears rather slender in dorsal view and in
+the White-winged Dove has an enlarged lateral belly that gives the
+appearance of a thicker muscle. In the Zenaida Dove _M.
+pseudotemporalis profundus_ is intermediate in shape between those of
+the other two species. This muscle will be discussed in detail later.
+
+~_M. protractor pterygoidei._~--The origin is fleshy from the junction
+of the sphenoidal rostrum and the interorbital septum. Fibers converge
+on the pterygoid in anteroventrolateral and posteroventrolateral
+directions. The posterior edge of the muscle is in contact with _M.
+protractor quadrati_ with which its fibers mingle. The insertion is
+fleshy on the posterior surface of the lateral half of the pterygoid to
+its articulation with the body of the quadrate (figs. 6, 8, 9, 11,
+13-20).
+
+~_M. depressor mandibulae superficialis medialis._~--The origin is
+fleshy from the lateral edge of the basioccipital where the muscle is
+attached to _Ligamentum depressor mandibulae_ and extends in a lateral
+direction to a point where the structures involved turn dorsad. The
+insertion is by fibers and a light aponeurosis on the crista that is
+situated on the posteroventromedial edge of the lower mandible.
+
+~_M. depressor mandibulae superficialis lateralis._~--The origin is
+fleshy from the squamosal region, slightly posteroventral to the origin
+of _M. adductor mandibulae externus superficialis_. A thin aponeurosis
+lies medial to the muscle fibers. The insertion is by means of an
+aponeurosis that becomes tendonlike along the posteroventrolateral
+crista and the posteriormost part of the ventral edge of the lower
+mandible.
+
+~_M. depressor mandibulae medialis._~--The origin is fleshy from the
+lateral and ventral surfaces of _Ligamentum depressor mandibulae_. The
+insertion is fleshy on the posterior surface of the lower mandible,
+posterodorsal to the insertions of _partes superficialis medialis et
+lateralis_ (figs. 4, 9, 10, 13 and 14).
+
+The parts of _M. depressor mandibulae_ are difficult to distinguish
+from one another because of considerable intermingling of fibers.
+
+~_M. pseudotemporalis superficialis._~--The origin is fleshy from the
+posterior wall of the orbit, dorsal to the foramen of the trigeminal
+nerve, lateral to the origin of _M. protractor quadrati_ and medial to
+_M. adductor mandibulae externus profundus_. The insertion is by means
+of an aponeurosis that bifurcates at the point of contact with the
+mandibular ramus of the trigeminal nerve, which is at the level of the
+orbital process of the quadrate (except in the Mourning Dove where the
+division is more anterior), and which inserts as two tendons on the
+dorsomedial edge of the lower mandible posterior to the insertion of
+_M. pseudotemporalis profundus_. The lateral tendon is superficial to
+the dorsomedial edge of _M. adductor mandibulae externus_, and
+converges with the aponeurosis of _pars profundus_ of that muscle and
+inserts with it on a tubercle near the dorsomedial edge of the
+mandible anterior to the insertion of _M. adductor mandibulae
+posterior_ as mentioned before. The anterior half of the medial tendon
+lies ventral to the lateral edge of _M. pseudotemporalis profundus_ and
+the mandibular ramus of the trigeminal nerve. All of the fibers of the
+muscle insert on the posteroventral surface of the aponeurosis before
+it divides. Part of _M. pseudotemporalis profundus_ also lies ventral
+to the medial tendon of _M. pseudotemporalis superficialis_ and, in
+effect, the tendon is imbedded in the substance of _M. pseudotemporalis
+profundus_ as it proceeds anteriorly. The trigeminal nerve leaves a
+slight impression on the ventral surface of the muscle near its origin
+(figs. 1, 3, 11, 13, 14, 15 and 16).
+
+~_M. adductor mandibulae posterior._~--The origin is fleshy from the
+anterodorsal and anterior surfaces of the quadrate body, from the
+anterodorsolateral, medial and anterior surfaces of the orbital process
+of the quadrate. The muscle also has an origin from the otic process of
+the quadrate, partly fleshy and partly by a slight aponeurosis. The
+insertion is fleshy on the dorsal and lateral surfaces of the mandible
+immediately anterior to the articulating surface. This muscle also has
+extensive insertion on the medial side of the lower mandible dorsal to
+the insertion of _M. pterygoideus dorsalis medialis_ and posterior to
+the origin of _M. pseudotemporalis profundus_ (figs. 1, 3, 5, 17, 18,
+19 and 20).
+
+The fibers of _M. pseudotemporalis profundus_ can be distinguished from
+the fibers of _M. adductor mandibulae posterior_ because the
+pterygoideus nerve passes between the two (Lakjar, 1926:55). Rooth
+(1953:255-256) considers as part of this muscle the ventral aponeurosis
+of _pars profundus_ of _M. adductor mandibulae externus_ and all the
+fibers ventral to it. But I could not justify the inclusion of that
+aponeurosis as part of _M. adductor mandibulae posterior_ in the doves
+because none of the fibers of _M. adductor mandibulae posterior_ as I
+have described it were attached to that particular aponeurosis.
+
+~_M. protractor quadrati._~--The origin is fleshy from the posterior
+wall of the orbit medial to the foramen of the trigeminal nerve and
+also medial to the origin of _M. pseudotemporalis superficialis_. The
+origin describes an arc in the horizontal plane until it reaches the
+interorbital septum and the optic nerve. The insertion is fleshy on the
+posteromedial edge of the body of the quadrate and the orbital process
+of the quadrate and on the otic process of the quadrate. The muscle
+also inserts on the ventromedial surface of the orbital process of the
+quadrate and the adjacent area of the body of the quadrate (figs. 5, 7,
+9, 11, 13-18).
+
+_M. protractor quadrati_ possesses many fibers that arise from _M.
+protractor pterygoidei_. Consequently, it is difficult to determine the
+exact extent of the origin or the insertion of either muscle.
+
+
+ACTION OF JAW MUSCLES
+
+~_M. pterygoideus ventralis._~--Contraction of this muscle retracts the
+upper mandible by moving the palatine posteriorly, and simultaneously
+adducts the lower mandible.
+
+~_M. pterygoideus dorsalis._~--This muscle functions in essentially the
+same manner as _M. pterygoideus ventralis_. The result of having a part
+of its origin on the pterygoid as well as on the palatine is to
+facilitate retraction of the upper mandible.
+
+~_M. adductor mandibulae._~--This is the chief adductor of the lower
+mandible and the muscle functions solely in that capacity. In birds
+having great crushing ability, this muscle is much larger and more
+powerful and the skull is reinforced behind the quadrate in order to
+withstand the pressure of the lower mandible against the quadrate
+during adduction (Sims, 1955:374 and Bowman, 1961:219-222).
+
+~_M. pseudotemporalis profundus._~--With origin and insertion on highly
+movable bones, this muscle, when it contracts, retracts the upper
+mandible and adducts the lower mandible. Like the pterygoid muscles,
+this muscle, by itself, would allow the bird to grasp objects by means
+of its mandibles. However, _M. pseudotemporalis profundus_ could
+produce a more powerful grip because it takes origin farther anteriorly
+on the lower mandible.
+
+~_M. protractor pterygoidei._~--Contraction of _M. protractor
+pterygoidei_ pulls the pterygoid anteromedially and causes it to slide
+forward along the sphenoidal rostrum. This action aids in protraction
+of the upper mandible.
+
+~_M. depressor mandibulae._~--The depressor of the lower mandible is
+the sole muscle other than _M. geniohyoideus_ involved in the function
+of abducting the lower jaw of doves. Its size can be correlated
+especially well with feeding habits of the bird. Other birds that force
+their closed mandibles into fruit, wood or the earth and then forcibly
+open them, belong to groups possessing enlarged depressors. Contraction
+of the muscle pulls the postarticular (retroarticular) process upward
+with the resultant downward movement of that part of the mandible which
+is anterior to the articulation. Since there is no "gaping" in doves
+the muscle is only large enough to overcome the inherent tone of the
+relaxed adductor muscles.
+
+In some non-passerine species as well as in certain passerines the
+muscle also serves to raise the upper jaw by acting on the quadrate,
+which is capable of rotating vertically on its otic process. Especially
+in the gapers, where resistance is offered near the tip of the lower
+mandible, contraction of the muscle pulls the entire mandible dorsad
+thus forcing the jugal and palatal struts forward (Zusi, 1959:537-539).
+The action supplements that of _Mm. protractor pterygoidei et quadrati_
+and is enhanced by anterior migration of the origin of _M. depressor
+mandibulae_.
+
+There is no lifting action involved in contraction of the depressor
+muscle in doves for two reasons--(A) the origin of the muscle is
+situated much too far posteriorly on the skull, and, more important,
+(B) the quadrate is not hinged for vertical movement. As will be
+discussed later, it moves only in a horizontal plane.
+
+~_M. pseudotemporalis superficialis._~--Like _M. adductor mandibulae_,
+this muscle performs only the one function of adducting the lower
+mandible, and like _M. pseudotemporalis profundus_ it is a synergist of
+that muscle.
+
+~_M. adductor mandibulae posterior._~--Although this muscle undoubtedly
+acts as an adductor of the lower mandible, I believe that, because of
+its disadvantageous insertion so near the articulation, its main
+function must be concerned with firming the mandible against the
+quadrate. This is to say that its function is partially that of a
+ligament.
+
+~_M. protractor quadrati._~--When _M. protractor quadrati_ contracts,
+the quadrate bone is swung medially. This action, as mentioned
+previously, results in protraction of the upper jaw, and, as a
+consequence, its action supplements the action of _M. protractor
+pterygoidei_.
+
+
+CRANIAL OSTEOLOGY
+
+The ability of most birds to protract the upper mandible, and the
+structure of the skull which enables them to do so are responsible for
+common reference to the skull as "kinetic" (Beecher, 1951a:412; Fisher,
+1955:175). The movement is effected by muscular action on a series of
+movable bones that exert their forward force on the upper mandible,
+which in turn swings on a horizontal hinge, the "naso-frontal hinge,"
+at the base of the beak. The bone initiating the movement is the
+quadrate, which is hinged posteriorly by its otic process and which
+ordinarily swings up or down depending on the muscle or muscles being
+contracted at any given moment. The upward swing of the quadrate pushes
+the jugal bar, which is attached to its lateral tip, along its
+longitudinal axis, in an anterodorsal direction, and the force is
+transferred to the upper mandible, which is thereby elevated. A
+synergetic mechanism is simultaneously initiated by the same bone--the
+quadrate. Since the quadrate body articulates with the pterygoid, the
+upward movement forces the pterygoid to slide along a ridge in the
+ventral midline of the cranium, the sphenoidal rostrum, thus pushing
+the palatine forward and exerting an upward push on the upper mandible.
+
+In the columbids the quadrate has a bifurcated otic process that
+functions as the hinge. The posterior tips of the forks are situated
+almost vertically (one above the other) and the movement of the
+quadrate is not so much up and down, or vertical, as it is horizontal
+(fig. 12). When the quadrate moves medially the upper mandible is
+protracted; a lateral movement results in retraction. There is a
+slight, almost negligible, upward movement of the quadrate. The
+movements of the various bony elements were observed on a skull that
+had been made flexible by boiling in water for a minute as suggested by
+Beecher (1951a:412).
+
+Also in the columbids the naso-frontal hinge is not constructed in the
+same manner as it is in many other birds as there is not a simple hinge
+across the entire base of the beak. In fact, there is no true hinge at
+all in the area of the nasals, but those bones are extremely thin and
+they bend or flex under pressure. Actually, the hinge is double or
+divided. One part is on either side of the nasals. The hinges are
+situated at the posterodorsal tips of two thin processes of the
+maxillary bones and the appearance is not unlike that of half a span of
+a suspension bridge having the hinges at the tops of the towers.
+Several other species of birds share this type of hinge construction
+with columbids.
+
+The movement of the lower jaw is, of course, the primary operation
+involved in opening the mouth. The lower jaw possesses a deep fossa at
+its posterior end, or on its posterodorsal surface, which articulates
+with the body of the quadrate bone. The length of that part of the
+mandible extending behind the articulation is directly correlated with
+the resistance offered the mandible in opening, since it is on the
+posterior extension that the depressor of the lower mandible inserts.
+The larger the muscle the more surface is needed for attachment. Also
+the added length of the mandible posterior to the articulation serves
+as a lever in opening the mandible, and the fulcrum is moved relatively
+farther forward.
+
+In birds lacking resistance to abduction of the lower mandible, as in
+doves, it is nevertheless necessary for a slight postarticular process
+to remain for the insertion of a small depressor muscle which, as
+mentioned previously, is necessary to counteract the relaxed adductor
+muscles of the lower jaw.
+
+There are many exceptions to the rule that birds have kinetic skulls,
+and usually a secondary fusion and reinforcement of bones around the
+hinge has limited or eliminated all movement. Sims (1955) describes the
+Hawfinch's immobile upper jaw, which is used as a powerful press in
+cracking the stones of fresh fruit. Skulls of woodpeckers have been
+modified somewhat in the same manner as a result of their foraging and
+nesting habits (Burt, 1930).
+
+The two most distantly related members of the genera under
+investigation are the White-winged Dove, _Zenaida asiatica_, and the
+Mourning Dove, _Zenaidura macroura_. They were chosen to demonstrate
+differences and likenesses in proportions of members of the genera.
+
+Ten measurements were taken on each skull, but simple observation
+reveals that, in relation to total length of the skull, the beak of the
+White-winged Dove is longer than that of the Mourning Dove. Tip of
+upper mandible to base of beak averaged 48.6 and 42.9 per cent of the
+total length of the skull in the White-winged Dove and Mourning Dove,
+respectively. The position of the jugal bar has remained about the same
+with respect to the cranial part of the skull, and the entire cranial
+part of the skull is almost the same shape in the species studied.
+
+Likewise, in the White-winged Dove the distance from the anterior tip
+of the lower mandible to the anterior part of _M. adductor mandibulae
+externus_ is relatively longer in relation to the length of the lower
+mandible than in the Mourning Dove. Finally, the position of the jugal
+with respect to the naso-frontal hinge is about the same in the two
+species.
+
+Measurements and calculations indicate that the longer beak of the
+White-winged Dove as compared with the Mourning Dove is a function of
+the beak itself, not of differences in other parts of the skull.
+Measurements of skulls of Eared and Zenaida doves support this view.
+
+
+OTHER MORPHOLOGICAL FEATURES
+
+In the species dissected, the only variable muscle that I consider
+significant in revealing relationships is _M. pseudotemporalis
+profundus_. It is markedly enlarged in the White-winged Dove in
+relation to the homologous muscle in the Mourning Dove. The muscle is
+enlarged in such a manner that a lateral expansion of its mass is
+apparent in superficial or dorsal view (compare figures 15 and 16).
+This, of course, indicates a muscle with powerful contraction, which
+has been unable to enlarge its circumference symmetrically because the
+eye is immediately dorsal to the muscle. Therefore it has expanded
+laterally. Ventral expansion is blocked by the presence of other
+muscles, and medially there is no surface for the insertion of
+additional fibers on the orbital process of the quadrate.
+
+The jaw musculature has been known for some time to be highly adaptive
+(Beecher, 1951a and b, 1953; Bowman, 1961; Burt, 1930; Engels, 1940 and
+Goodman and Fisher, 1962) and it would not be unreasonable, I think, to
+expect the jaw muscles of closely related species with similar habits
+to be similar. The beak of the White-winged Dove is longer in
+proportion to the length and height of the skull (exclusive of the
+beak) than is the beak of the Mourning Dove. The lengthened beak is
+probably an adaptation for nectar-feeding, which has been documented by
+McGregor, Alcorn and Olin (1962:263-264) while investigating
+pollinating agents of the Saguaro Cactus (_Cereus giganteus_), and by
+Gilman (1911:53) who observed the birds thrusting their bills into the
+flowers of the plant. Gilman indicated, however, that he could not be
+sure if the birds were seeking insects, pollen, or nectar. In any event
+the lengthened bill probably facilitates getting food by birds that
+probe parts of flowers. Hensley (1954:202) noted that both Mourning and
+White-winged doves were "exceptionally fond of this source of
+nourishment." But he also points out an "interesting correlation"
+between the presence of the white-wings in the desert and the flowering
+of the saguaro. During his studies the appearance of the first
+white-wing preceded the opening of the first saguaro flower by two
+days. The flowering and fruiting season lasted until August, the month
+of termination of the white-wing breeding season.
+
+Since Hensley makes the correlation solely with the white-wings, I
+assume that there is no other obvious correlation between plants and
+birds among the remainder of the avifauna of the desert. Probably the
+Mourning Dove has failed to adapt to nectar-feeding as yet, and the
+White-winged Dove is the primary exploiter of this food niche. It
+should be noted, also, that the head of the Mourning Dove is smaller
+than the white-wing's, and perhaps there is no need for an elongated
+beak for reaching deeply into the flowers.
+
+The lengthened bill should produce no difficulties in protraction of
+the upper mandible and depression of the lower for the reason that in
+the dove there is no known resistance offered to these movements. The
+genus _Icterus_ furnishes an example wherein resistance is met in the
+process of opening the mandibles; individuals of this genus thrust
+their closed bill into certain fruits and forcibly open their mandibles
+against the resistance of the pulp by strong protraction and
+depression, thus permitting the juices of the fruit to lake and
+ultimately to be consumed (Beecher, 1950:53). Beecher refers to the
+technique used in fruit-eating as "gaping." The result of gaping in
+_Icterus_ should be the presence of a more massive set of muscles
+concerned with protraction and depression than is found in non-gaping
+groups. Beecher found the situation to be exactly as expected in that
+genus and in other genera which also gape. Meadowlarks (_Sturnella_)
+and caciques (_Archiplanus_) gape and pry in soil and wood respectively
+(Beecher, 1951a:422 and 426).
+
+The lengthened beak would be a problem when the White-winged Dove
+attempted to pick up objects such as seeds, which do in fact constitute
+the largest percentage of its diet in spite of its nectar-feeding
+habit. A similar situation exists in the genus _Icterus_, which is
+primarily adapted for gaping even though it shows a preference for
+insects when they are abundant (Beecher, 1950:53). The lengthened beak
+could be compensated for by (A) migration of the anterior end of the
+jugal bar toward the rostral tip of the bill and away from the
+fronto-nasal hinge with a simultaneous enlargement of the adductor
+muscles of the lower mandible, or (B) enlargement of the one muscle
+that functions simultaneously as an efficient retractor of the upper
+mandible and adductor of the lower mandible, namely _M.
+pseudotemporalis profundus_. _Mm. pterygoideus dorsalis et lateralis_
+perform the same function, but because of their position on the lower
+mandible they, apparently, are stronger retractors of the upper
+mandible than they are adductors of the lower.
+
+It will be recalled that the jugal bar bears the same, or nearly the
+same, relationship to the cranium in the white-wing as it does in the
+Mourning Dove and that the heads, excluding the beaks of both species,
+are of nearly the same proportions. Also, _Mm. adductor mandibulae
+externus_ and _pseudotemporalis superficialis_, the chief adductor
+muscles of the lower mandible, were not noticeably enlarged in the
+white-wing. It is also important to note that other combinations of
+migration of bone and/or enlargement of muscles could successfully
+solve the problem of providing sufficient leverage for the proper
+functioning of the lengthened mandibles, but it is my thesis that the
+second alternative sufficed for seed-eating habits and that that is the
+adaptation that was established; it is, in fact, the only one present
+in the White-winged Dove.
+
+It is unlikely that this enlarged muscle and beak are the remains of
+another series of jaw muscles that have converged toward the condition
+in Mourning Doves. Columbids are almost unquestionably monophyletic,
+and two lines would have had to diverge and then converge. There is no
+evidence for such an evolutionary occurrence.
+
+
+GENERIC RELATIONSHIP
+
+An attempt will be made here to summarize all the available evidence,
+direct or indirect, which bears on the problem of relationship of these
+genera. The original dissections which are discussed in this report are
+only valuable as one more bit of evidence concerning one characteristic
+that aids in clarification of generic relationship, and it is only in
+conjunction with other evidence that any satisfactory conclusion may be
+forthcoming.
+
+
+Morphology
+
+My dissections demonstrated that, in relation to the size of the doves,
+the jaw musculature of all the specimens investigated was so nearly
+alike that only one major difference was detected. _M. pseudotemporalis
+profundus_ appeared to be enlarged in the White-winged Dove. This might
+have been predicted, since the white-wing was also shown to possess an
+elongated beak, presumably an adaptation for nectar-feeding, which
+would necessitate additional muscle development in order to compensate
+for the added length. Measurements recorded from several skulls
+indicated that the heads of the birds (excluding the beak) are nearly
+proportional.
+
+Perhaps plumage patterns are the most widely used characters for
+determining generic relationships of birds. Ridgway (1916:339-385)
+followed the columbid classification of Salvadori (1893) using plumage
+patterns and body proportions to distinguish between the genera. In the
+genus _Zenaidura_ he included the unique specimen _Zenaidura
+yucatanensis_, and he placed _auriculata_ in _Zenaida_. The
+White-winged Dove was referred to a separate genus, _Melopelia_. He
+described the genus _Zenaidura_ in the following manner:
+
+ "Plumage of head, neck and under parts soft and blended;
+ bare orbital space moderate, broadest beneath eyes.
+ Coloration plain, the proximal secondaries (sometimes
+ adjacent wing-coverts and scapulars also) spotted with
+ black; rectrices (except middle pair) with a black band
+ across postmedian portion, the apical portion paler gray
+ than basal portion, sometimes white; a small black
+ subauricular spot; adult males with head, neck and anterior
+ under parts more or less vinaceous and sides of neck glossed
+ with metallic purple."
+
+He noted that the plumage of _Zenaida_ was almost precisely as
+described for _Zenaidura_. Also, although all members of _Zenaida_
+reputedly possessed twelve rectrices, a characteristic of the genus, it
+was later found that _auriculata_ possessed fourteen rectrices. The
+species was promptly placed in the genus _Zenaidura_ by Peters
+(1934:213-215). In plumage and coloration, _Melopia_ was described as
+similar to _Zenaida_ and _Zenaidura_ but without black spots on the
+wings.
+
+The White-winged Dove also has twelve rectrices, but Bond (1940:53) and
+Goodwin (1958:330-334) considered the number and shape of rectrices to
+be of minor importance when compared to the homologous markings of the
+plumage. Goodwin stated that his conclusion was emphasized by the fact
+that the tail of _auriculata_ is intermediate in length and shape
+between those of _macroura_ and _aurita_. In summary Goodwin "lumped"
+the genera _Zenaida_ and _Zenaidura_ under the genus _Zenaida_.
+
+
+Nidification
+
+It has been adequately documented that members of these genera closely
+resemble one another in their nesting and egg-laying habits. Bent
+(1932:407, 417), Davie (1889:157), Goss (1891:242) and Nice (1922:466)
+have described the two, white eggs of the clutch of the Mourning Dove.
+They have also noted that their nests are composed mainly of twigs and
+may be constructed in trees, shrubs or on the ground. The Eared Dove
+has nearly identical habits (Bond, 1961:104), and a similar situation
+exists with the Zenaida Dove (Audubon, 1834:356; Bent, 1932:418-419).
+
+Like the other species, White-winged Doves lay two white or buffy eggs
+per clutch and build frail nests of sticks (Bent, 1932:431; Wetmore,
+1920:141; Baird, Brewer and Ridgway, 1905:377).
+
+The point to be made here is simply this: If the species in question
+are to be considered congeneric then it might reasonably be expected
+that they would display some similarity in nidification and egg-laying.
+If their habits varied considerably it would not necessarily mean that
+their relationship was more distant, but similarities can usually be
+considered indicative of affinities because they are the phenotypic
+expression of the partially unaltered genotype of the common ancestor.
+
+
+Interbreeding
+
+Intergeneric crosses of columbids in captivity are common, but in
+nature there is little evidence that even interspecific crosses occur.
+Only one apparent hybrid between members of the genus _Zenaida_ and
+genus _Zenaidura_ has ever been discovered. The individual was taken on
+the Yucatan peninsula of Mexico, and was described and named as a new
+species (_Zenaidura yucatanensis_).
+
+Salvadori (1893:373), Ridgway (1916:353) and Peters (1934:213-215)
+agree that _Zenaidura yucatanensis_ Lawrence is a hybrid between
+_Zenaidura macroura marginella_ and _Zenaida aurita yucatanensis_.
+Ridgway (1916:355), however, notes that "... If _Zenaidura
+yucatanensis_ Lawrence should prove to be really a distinct species,
+and not a hybrid ... unquestionably _Zenaida_ and _Zenaidura_ can not
+be separated generically, since the former is in every way exactly
+intermediate between the two groups." In the event that the unique type
+is a hybrid, the very fact of its existence supports the hypothesis
+that the genera are more closely related than is currently recognized.
+
+
+Serology
+
+There have been no investigations having as their sole purpose the
+clarification of the relationship of the genera _Zenaida_ and
+_Zenaidura_. But some work has involved the comparison of the antigenic
+content of individual columbids with the antigenic content of a member
+of another species of the same family.
+
+Irwin and Miller (1961) tested, along with other columbids, members of
+_Zenaida_ and _Zenaidura_ for presence of, 1) species-specific antigens
+of _Columba guinea_ (in relation to _Columba livia_) which are
+designated A, B, C and E, and, 2) species-specific antigens of _C.
+livia_ (in relation to _C. guinea_) which are designated A', B', C' and
+E'.
+
+In the first test all five species of _Zenaida_ and _Zenaidura_
+possessed antigens A and C, and all but _auriculata_ possessed E. None
+of the species gave evidence of the presence of the B antigen of _C.
+guinea_ in their blood. In the latter test only _macroura_ had A', only
+_asiatica_ had B' (_aurita_ was not tested for B'), and none had C' or
+E'.
+
+These results would indicate that the five species are similar
+regarding antigenic content of the blood, and the variation is not
+consistent within one or the other genus as presently known.
+
+
+SUMMARY AND CONCLUSION
+
+The avian genus _Zenaida_ is currently considered to be distinct from
+the genus _Zenaidura_ by most columbid taxonomists. The jaw muscles of
+six Mourning Doves (_Zenaidura_) and five White-winged Doves
+(_Zenaida_) were investigated as to differences and similarities that
+might clarify the relationships of the genera. The sizes and
+proportions of skulls were also considered in 37 Mourning and
+White-winged doves and two Eared Doves. Larger size of _M.
+pseudotemporalis profundus_, the muscle that functions simultaneously
+as an adductor of the lower jaw and retractor of the upper jaw, in the
+White-winged Dove was the character found in the jaw musculature that
+could be used to support the contention that _Zenaidura_ and _Zenaida_
+represent distinct genera. Larger size of this muscle in the white-wing
+seems to be related to its elongated beak. The long beak apparently is
+used for nectar-feeding in flowers of the Saguaro Cactus.
+
+Excluding the beak, skulls of the white-wing and Mourning doves are of
+nearly the same shape. Previous investigators have shown that in
+_Zenaida_ and _Zenaidura_ plumage patterns are similar, nesting habits
+and eggs are nearly identical, blood proteins are similar, and one
+"intergeneric" hybridization in nature is known.
+
+Consequently, it is concluded that species of the two alleged genera
+are congeneric, and I agree with Goodwin (1958) that the genus
+_Zenaida_ (Bonaparte, 1838:41) should include the Mourning Dove, Eared
+Dove, Socorro Dove, Zenaida Dove, and White-winged Dove. Their Latin
+binomina are _Zenaida macroura_, _Zenaida auriculata_, _Zenaida
+graysoni_, _Zenaida aurita_, and _Zenaida asiatica_, respectively.
+
+[Illustration: FIG. 1. Medial view of left ramus of lower
+mandible of Mourning Dove. x 2-1/2.
+
+FIG. 2. Lateral view of right ramus of lower mandible of
+Mourning Dove. x 2-1/2.]
+
+[Illustration: FIG. 3. Dorsal view of lower mandible of
+Mourning Dove. x 2-1/2.
+
+FIG. 4. Ventral view of lower mandible of Mourning Dove.
+x 2-1/2.]
+
+[Illustration: FIG. 5. Dorsal view of right quadrate of
+Mourning Dove. x 5.
+
+FIG. 6. Dorsal view of right pterygoid of Mourning Dove. x 5.
+
+FIG. 7. Ventral view of right quadrate of Mourning Dove. x 5.
+
+FIG. 8. Ventral view of right pterygoid of Mourning Dove. x 5.]
+
+[Illustration: FIG. 9. Right lateral view of skull of Mourning
+Dove. x 2-1/2.
+
+FIG. 10. Ventral view of skull of Mourning Dove. x 2-1/2.]
+
+[Illustration: FIG. 11. Cross section of skull of Mourning Dove;
+anterior view. x 2-1/2.
+
+FIG. 12. Dorsal view of right quadrate of Mourning Dove showing
+movement which protracts the upper mandible (broken line). x 5.]
+
+[Illustration: FIG. 13. Right lateral view of the jaw musculature of
+the White-winged Dove; superficial layer, x 5.
+
+FIG. 14. Right lateral view of the jaw musculature of the Mourning
+Dove; superficial layer. x 5.]
+
+[Illustration: FIG. 15. Dorsal view of the jaw musculature of the
+White-winged Dove (right side); superficial layer. x 5.
+
+FIG. 16. Dorsal view of the jaw musculature of the Mourning Dove
+(right side); superficial layer. x 5.]
+
+[Illustration: FIG. 17. Dorsal view of the jaw musculature of the
+White-winged Dove (right side); middle layer. x 5.
+
+FIG. 18. Dorsal view of the jaw musculature of the Mourning Dove
+(right side); middle layer. x 5.]
+
+[Illustration: FIG. 19. Dorsal view of the jaw musculature of the
+White-winged Dove (right side); deep layer. x 5.
+
+FIG. 20. Dorsal view of the jaw musculature of the Morning Dove (right
+side); deep layer. x 5.]
+
+[Illustration: FIG. 21. Ventral view of the jaw musculature of the
+White-winged Dove (_M. depressor mandibulae_ not shown). x 5.
+
+FIG. 22. Ventral view of the jaw musculature of the Mourning Dove
+(_M. depressor mandibulae_ not shown). x 5.]
+
+
+
+
+LITERATURE CITED
+
+
+ADAMS, L. A.
+ 1919. A memoir on the phylogeny of the jaw muscles in recent and
+ fossil vertebrates. Annals New York Acad. Sci., 28:51-166.
+
+AUDUBON, J. J.
+ 1834. Ornithological biography. Vol. II. Adam & Charles Black,
+ Edinburgh, xxxii + 588 pp.
+
+BAIRD, S. F., BREWER, T. M., and RIDGWAY, R.
+ 1905. The land birds of North America. Little, Brown, and Company,
+ Boston, 560 + xxvii pp.
+
+BEECHER, W. J.
+ 1950. Convergent evolution in the American orioles. Wilson Bull.
+ 62:51-86.
+
+ 1951a. Adaptations for food-getting in the American blackbirds. Auk,
+ 68:411-440.
+
+ 1951b. Convergence in the Coerebidae. Wilson Bull., 63:274-287.
+
+ 1953. A phylogeny of the oscines. Auk, 70:270-333.
+
+BENT, A. C.
+ 1932. Life histories of North American gallinaceous birds. Bull.
+ U. S. Nat. Mus., 162:xi + 490 pp., 93 pls.
+
+BONAPARTE, C. L.
+ 1838. Geographical and comparative list of the birds of Europe and
+ North America. John Van Voorst, London, vii + 68 pp.
+
+BOND, J.
+ 1961. Birds of the West Indies. Houghton Mifflin Company, Boston.
+ 256 pp., 8 pls., 186 figs.
+
+BOWMAN, R. I.
+ 1961. Morphological differentiation and adaptation in the Galapagos
+ finches. Univ. California Publ. Zool., 58:vii + 302 pp.,
+ 22 pls., 74 figs., 63 tables.
+
+BURT, W. H.
+ 1930. Adaptive modifications in the woodpeckers. Univ. California
+ Publ. Zool., 32:455-524.
+
+CAIN, A. J.
+ 1956. The genus in evolutionary taxonomy. Syst. Zool., 5:97-109.
+
+ 1959. Taxonomic concepts. Ibis, 101:302-318.
+
+DAVIE, O.
+ 1889. Nests and eggs of North American birds. Hann & Adair,
+ Columbus, 455 + xii pp., 13 pls.
+
+EDGEWORTH, F. H.
+ 1935. The cranial muscles of vertebrates. Cambridge Univ. Press,
+ viii + 493 pp., 841 figs.
+
+ENGELS, W. L.
+ 1940. Structural adaptations in thrashers (Mimidae: genus
+ _Toxostoma_) with comments on interspecific relationships.
+ Univ. California Publ. Zool., 42:341-400, 24 figs., 11 tables.
+
+FISHER, H. I.
+ 1955. Some aspects of the kinetics in the jaws of birds. Wilson
+ Bull., 67:175-188, 4 figs., 6 tables.
+
+GADOW, H.
+ 1891. Vogel: I. Anatomischer Theil. Bronn's Klassen und Ordnungen
+ des Thier-Reichs. C. F. Winter, Leipzig, 6:1-1,008, many
+ figs., 59 pls.
+
+GILMAN, M. F.
+ 1911. Doves on the Pima Reservation. Condor, 13:51-56.
+
+GOODMAN, D. C., and FISHER, H. I.
+ 1962. Functional anatomy of the feeding apparatus in waterfowl.
+ Southern Illinois Univ. Press, Carbondale, xii + 193 pp.
+
+GOODWIN, D.
+ 1958. Remarks on the taxonomy of some American doves. Auk,
+ 75:330-334.
+
+GOSS, N. S.
+ 1891. History of the birds of Kansas. Geo. W. Crane & Co., Topeka,
+ 692 pp., 35 pls.
+
+HENSLEY, M. M.
+ 1954. Ecological relations of the breeding bird populations of the
+ desert biome of Arizona. Ecol. Monographs, 24:185-207.
+
+HOFER, H.
+ 1950. Zur Morphologie der Kiefermuskulatur der Vogel. Zool. Jahrb.
+ Jena (Anat.), 70:427-556, 44 figs.
+
+IRWIN, M. R., and MILLER, W. J.
+ 1961. Interrelationships and evolutionary patterns of cellular
+ antigens in columbidae. Evolution, 15:30-43.
+
+JACKSON, A. S.
+ 1941. The mourning dove in Throckmorton County, Texas, Unpubl.
+ manuscript (Abstract).
+
+KIEL, W. H., JR., and HARRIS, J. T.
+ 1956. Status of the white-winged dove in Texas. Trans. 21st N.
+ Amer. Wildl. Conf., pp. 376-388.
+
+KNAPPEN. P.
+ 1938. Preliminary report on some of the important foods of the
+ mourning dove in the southeastern U. S. Trans. 3rd N. Amer.
+ Wildl. Conf., pp. 776-781.
+
+LAKJER, T.
+ 1926. Studien Uber die Trigeminus-versorgte Kaumuskulatur der
+ Sauropsiden. C. A. Reitzel Buchhandlung, Kopenhagen, 154 pp.,
+ 26 pls.
+
+LEOPOLD, A. S.
+ 1943. Autumn feeding and flocking habits of the mourning dove in
+ southern Missouri. Wilson Bull., 55:151-154.
+
+MCGREGOR, S. E., ALCORN, S. M., and OLIN, G.
+ 1962. Pollination and pollinating agents of the saguaro. Ecology,
+ 43:259-267.
+
+NICE, M. M.
+ 1922. A study of the nesting of mourning doves. Auk, 39:457-474;
+ 40:37-58.
+
+PETERS, J. L.
+ 1934. The classification of some American pigeons. Condor,
+ 36:213-215.
+
+ 1937. Check-list of birds of the world. Vol. III. Harvard Univ.
+ Press, Cambridge, xiii + 311 pp.
+
+ROOTH, J.
+ 1953. On the correlation between the jaw muscles and the structure
+ of the skull in _Columba palumbus_. Kon. Ned. Akad. Wet.;
+ Proc. Sect. Sci., Vol. VI, serie C, pp. 251-264.
+
+SALVADORI, T.
+ 1893. Catalogue of birds in the British Museum, 21:xvii + 676 pp.,
+ 15 pls. + 17 pp.
+
+SHUFELDT, R. W.
+ 1890. The myology of the raven. MacMillan & Co., London, xix + 343
+ pp., 76 figs.
+
+SIMS, R. W.
+ 1955. The morphology of the head of the hawfinch. Bull. Brit. Mus.
+ (Nat. Hist.) Zool., 2:369-393.
+
+WETMORE, A.
+ 1920. Observations of the habits of the white-winged dove. Condor,
+ 22:140-146.
+
+ZUSI, R. L.
+ 1959. The function of the depressor mandibulae muscle in certain
+ passerine birds. Auk, 76:537-539.
+
+
+_Transmitted June 3, 1963._
+
+
+
+
+ * * * * *
+
+Transcriber's Notes
+
+Italicized text is shown within _underscores_.
+
+Bold italicized text is shown within ~_tildes and underscores_~.
+
+
+
+
+
+
+
+
+End of the Project Gutenberg EBook of Jaw Musculature of the Mourning and
+White-winged Doves, by Robert L. Merz
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