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Fringillidae, by William B. Stallcup

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Title: Myology and Serology of the Avian Family Fringillidae
       A Taxonomic Study

Author: William B. Stallcup

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  ==================================================================
                  UNIVERSITY OF KANSAS PUBLICATIONS
                     MUSEUM OF NATURAL HISTORY


          Volume 8, No. 2, pp. 157-211, figures 1-23, 4 tables

  ----------------------  November 15, 1954  ----------------------


                         Myology and Serology
                    of the Avian Family Fringillidae,
                           A Taxonomic Study

                                  BY
                          WILLIAM B. STALLCUP


                         UNIVERSITY OF KANSAS
                               LAWRENCE
                                 1954




     UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

          Editors: E. Raymond Hall, Chairman, A. Byron Leonard,
                   Robert W. Wilson


          Volume 8, No. 2, pp. 157-211, figures 1-23, 4 tables
                    Published November 15, 1954





                         UNIVERSITY OF KANSAS
                           Lawrence, Kansas





                              PRINTED BY
                   FERD VOILAND, JR., STATE PRINTER
                            TOPEKA, KANSAS
                                 1954
                             [Union Label]
                               25-4632




                         Myology and Serology
                    of the Avian Family Fringillidae,
                           A Taxonomic Study

                                  BY
                          WILLIAM B. STALLCUP




CONTENTS


                                                                 PAGE

 INTRODUCTION                                                     160

 MYOLOGY OF THE PELVIC APPENDAGE                                  162
   General Statement                                              162
   Materials and Methods                                          163
   Description of Muscles                                         164
   Discussion of Myological Investigations                        175

 COMPARATIVE SEROLOGY                                             185
   General Statement                                              185
   Preparation of Antigens                                        186
   Preparation of Antisera                                        188
   Methods of Serological Testing                                 188
   Experimental Data                                              190
   Discussion of Serological Investigations                       190

 CONCLUSIONS                                                      201

 SUMMARY                                                          208

 LITERATURE CITED                                                 210




INTRODUCTION


The relationships of many groups of birds within the Order
Passeriformes are poorly understood. Most ornithologists agree that
some of the passerine families of current classifications are
artificial groups. These artificial groupings are the result of early
work which gave chief attention to readily adaptive external
structures. The size and shape of the bill, for example, have been
over-emphasized in the past as taxonomic characters. It is now
recognized that the bill is a highly adaptive structure and that it
frequently shows convergence and parallelism.

Since studies of external morphology have failed in some cases to
provide a clear understanding of the relationships of passerine birds,
it seems appropriate that attention be given to other morphological
features, to physiological features, and to life history studies in an
attempt to find other clues to relationships at the family and
subfamily levels.

This paper reports the results of a study of the relationships of some
birds of the Family Fringillidae and is based on the comparative
myology of the pelvic appendage and on the comparative serology of
saline-soluble proteins. Where necessary for comparative purposes,
birds from other families have been included in these investigations.

It has long been recognized that the Fringillidae include dissimilar
groups. Recent work by Beecher (1951b, 1953) on the musculature of the
jaw and by Tordoff (1954) primarily on the structure of the bony
palate has emphasized the artificial nature of the assemblage although
these authors disagree regarding major divisions within it (see
below).

The Fringillidae have been distinguished from other families of
nine-primaried oscines by only one character--a heavy and conical bill
(for crushing seeds). Bills of this form have been developed
independently in several other, unrelated, groups; as Tordoff (1954:7)
has pointed out, _Molothrus_ of the Family Icteridae, _Psittorostra_
of the Family Drepaniidae, and most members of the Family Ploceidae
have bills as heavy and conical as those of the fringillids. The
ploceids are distinguished from the fringillids by a single external
character: a fairly well-developed tenth primary whereas in
fringillids the tenth primary is absent or vestigial. Tordoff
(1954:20) points out, however, that this distinction is of limited
value since in other passerine families the tenth primary may be
present in some species of a genus and absent in others. The Genus
_Vireo_ is an example. Furthermore, at least one ploceid
(_Philetairus_) has a small, vestigial tenth primary, whereas some
fringillids (_Emberizoides_, for example) possess a tenth primary
which is rather large and ventrally placed (Chapin, 1917:253-254).
Thus, it is obvious that studies based on other features are necessary
in order to attain a better understanding of the relationships of the
birds involved.

Sushkin's studies (1924, 1925) of the structure of the bony and horny
palates have served as a basis for the division of the Fringillidae
into as many as five subfamilies (Hellmayr, 1938:v): Richmondeninae,
Geospizinae, Fringillinae, Carduelinae, and Emberizinae.

Beecher (1951b:280) points out that "the richmondenine finches arise
so uninterruptedly out of the tanagers that ornithologists have had
to draw the dividing line between the two groups arbitrarily." His
study of pattern of jaw-musculature substantiates this. He states
further that the cardueline finches arise without disjunction
from the tanagers. He suggests, therefore, that the two groups of
"tanager-finches" be made subfamilies of the Thraupidae and that a
third subfamily be maintained for the more typical tanagers. He states
that the emberizine finches are of different origin, arising from the
wood warblers (1953:307). Beecher (1951a:431; 1953:309) includes the
Dickcissel, _Spiza americana_, in the Family Icteridae, chiefly on the
basis of jaw muscle-pattern and the horny palate.

Tordoff (1954:10-11) presents evidence that the occurrence of
palato-maxillary bones in nine-primaried birds indicates relationship
among the forms possessing them. He points out that all fringillids
except the Carduelinae possess palato-maxillaries that are either free
or more or less fused to the prepalatine bar. He points out also that
in all carduelines, the prepalatine bar is flared at its juncture with
the premaxilla, and that the mediopalatine processes are fused across
the midline; noncardueline fringillids lack these characteristics. In
addition to the above he cites differences between the carduelines and
the "other" fringillids in the appendicular skeletons, in geographic
distribution, in patterns of migration, and in habits. Tordoff
concludes, therefore, that the carduelines are not fringillids but
ploceids, their closest affinities being with the ploceid Subfamily
Estrildinae. On the basis of palatal structure, the Fringillinae and
Geospizinae are combined with the Emberizinae, the name Fringillinae
being maintained for the subfamily. The tanagers merge with the
Richmondeninae on the one hand and with the Fringillinae on the other.
On this basis, Tordoff (1954:32) suggests that the Family Fringillidae
be divided into subfamilies as follows: Richmondeninae, Thraupinae,
and Fringillinae. The carduelines are placed as the Subfamily
Carduelinae in the Family Ploceidae.

From the foregoing, it is apparent that the two most recent lines of
research have given rise to conflicting theories regarding
relationships within the Family Fringillidae. The purpose of my
investigation, therefore, has been to gather information, from other
fields, which might clarify the relationships of these birds.

Since the muscle pattern of the leg in the Order Passeriformes is
thought to be one of long standing and slow change, any variation
which consistently distinguishes one group of species from another
could be significant. With the hope that such variation might be
found, a study of the comparative myology of the legs was undertaken.

The usefulness of comparative serology as a means of determining
relationship has been demonstrated in many investigations. Its use in
this instance was undertaken for several reasons: comparative serology
has its basis in biochemical systems which seem to evolve slowly; its
methods are objective; and its use has, heretofore, resulted in the
accumulation of data which seem compatible, in most instances, with
data obtained from other sources.

I acknowledge with pleasure the guidance received in this study from
Prof. Harrison B. Tordoff of the University of Kansas. I am indebted
also to Prof. Charles A. Leone without whose direction and assistance
the serological investigations would not have been possible; to
Professors E. Raymond Hall and A. Byron Leonard whose suggestions and
criticisms have been most helpful in the preparation of this paper;
and to T. D. Burleigh of the U. S. Fish and Wildlife Service for gifts
of several specimens used in this work. Assistance with certain parts
of the study were received from a contract (NR163014) between the
Office of Naval Research of the United States Navy and the University
of Kansas.




MYOLOGY OF THE PELVIC APPENDAGE


General Statement

In an excellent paper in which the muscles of the pelvic appendage of
birds are carefully and accurately described, Hudson (1937) reviewed
briefly the more important literature pertaining to the musculature of
the leg which had been published to that date. A review of such
information here, therefore, seems unnecessary.

Myological formulae suggested by Garrod (1873, 1874) have been
extensively used by taxonomists as aids in characterizing the orders
of birds. Relatively few investigations, however, involving the
comparative myology of the leg have been undertaken at family and
subfamily levels. The works of Fisher (1946), Hudson (1948), and
Berger (1952) are notable exceptions.

The terminology for the muscles used in this paper follows that of
Hudson (1937), except that I have followed Berger (1952) in Latinizing
all names. Homologies are not given since these are reviewed by
Hudson. Osteological terms are from Howard (1929).


Materials and Methods

Specimens were preserved in a solution of one part formalin to eight
parts of water. Thorough injection of all tissues was necessary for
satisfactory preservation. Most of the down and contour feathers were
removed to allow the preservative to reach the skin.

In preparing specimens for study, the legs and pelvic girdle were
removed and washed in running water for several hours to remove much
of the formalin. They were then transferred to a mixture of 50 per
cent alcohol and a small amount of glycerine.

All specimens were dissected with the aid of a low power binocular
microscope. Where possible, several specimens of each species were
examined for individual differences. Such differences were found to be
slight, involving mainly size and shape of the muscles. The size is
dependent partly on the age of the bird, muscles from older birds
being larger and better developed. The shape of a muscle (whether long
and slender or short and thick) is due in part to the position in
which the leg was preserved; that is to say, a muscle may be extended
in one bird and contracted in another. For these reasons, descriptions
and comparisons are based mainly on the origin and insertion of a
muscle and on its position in relation to adjoining muscles.

Birds dissected in this study are listed below (in the order of the A.
O. U. Check-List):

                               SPECIES

 _Vireo olivaceus_ (Linnaeus)        _Leucosticte tephrocotis_
 _Seiurus motacilla_ (Vieillot)         (Swainson)
 _Passer domesticus_ (Linnaeus)      _Spinus tristis_ (Linnaeus)
 _Estrilda amandava_ (Linnaeus)      _Loxia curvirostra_ Linnaeus
 _Poephila guttata_ (Reichenbach)    _Chlorura chlorura_ (Audubon)
 _Icterus galbula_ (Linnaeus)        _Pipilo erythrophthalmus_
 _Molothrus ater_ (Boddaert)            (Linnaeus)
 _Piranga rubra_ (Linnaeus)          _Calamospiza melanocorys_
 _Richmondena cardinalis_ (Linnaeus)    Stejneger
 _Guiraca caerulea_ (Linnaeus)       _Chondestes grammacus_ (Say)
 _Passerina cyanea_ (Linnaeus)       _Junco hyemalis_ (Linnaeus)
 _Spiza americana_ (Gmelin)          _Spizella arborea_ (Wilson)
 _Hesperiphona vespertina_ (Cooper)  _Zonotrichia querula_ (Nuttall)
 _Carpodacus purpureus_ (Gmelin)     _Passerella iliaca_ (Merrem)
 _Pinicola enucleator_ (Linnaeus)    _Calcarius lapponicus_ (Linnaeus)


Description of Muscles

The descriptions which follow are those of the muscles in the leg of
the Red-eyed Towhee, _Pipilo erythrophthalmus_. Differences between
species, where present, are noted for each muscle. The term thigh is
used to refer to the proximal segment of the leg; the term crus is
used for that segment of the leg immediately distal to the thigh.


_+Musculus iliotrochantericus posticus+_ (Fig. 2).--The origin of this
muscle is fleshy from the entire concave lateral surface of the ilium
anterior to the acetabulum. The fibers converge posteriorly, and the
muscle inserts by a short, broad tendon on the lateral surface of the
femur immediately distal to the trochanter. It is the largest muscle
which passes from the ilium to the femur.

Action.--Moves femur forward and rotates it anteriorly.

Comparison.--No significant differences noted among the species
studied.


_+Musculus iliotrochantericus anticus+_ (Fig. 3).--Covered laterally
by the _m. iliotrochantericus posticus_, this slender muscle
has a fleshy origin from the anteroventral edge of the ilium
between the origins of the _m. sartorius_ anteriorly and the _m.
iliotrochantericus medius_ posteriorly. The _m. iliotrochantericus
anticus_ is directed caudoventrally and inserts by a broad, flat
tendon on the anterolateral surface of the femur between the heads of
the _m. femorotibialis externus_ and _m. femorotibialis medius_ and
just distal to the insertion of the _m. iliotrochantericus medius_.

Action.--Moves femur forward and rotates it anteriorly.

Comparison.--No significant differences noted among the species studied.


_+Musculus iliotrochantericus medius+_ (Fig. 3).--Smallest of the
three _iliotrochantericus_ muscles, this bandlike muscle has a fleshy
origin from the ventral edge of the ilium just posterior to the origin
of the _m. iliotrochantericus anticus_. The fibers are directed
caudoventrally, and the insertion is tendinous on the anterolateral
surface of the femur between the insertion of the other two
_iliotrochantericus_ muscles.

Action.--Moves femur forward and rotates it anteriorly.

Comparison.--No significant differences noted among the species
studied.


_+Musculus iliacus+_ (Figs. 4, 5).--Arising from a fleshy origin on
the ventral edge of the ilium just posterior to the origin of the _m.
iliotrochantericus medius_, this small slender muscle passes
posteroventrally to its fleshy insertion on the posteromedial surface
of the femur just proximal to the origin of the _m. femorotibialis
internus_.

Action.--Moves femur forward and rotates it posteriorly.

Comparison.--No significant differences among the species studied.


_+Musculus sartorius+_ (Figs. 1, 4).--A long, straplike muscle, the
_sartorius_ forms the anterior edge of the thigh. The origin is
fleshy, half from the anterior edge of the ilium and from the median
dorsal ridge of this bone and half from the posterior one or two free
dorsal vertebrae. The insertion is fleshy along a narrow line on the
anteromedial edge of the head of the tibia and on the medial region of
the patellar tendon.

Action.--Moves thigh forward and upward and extends shank.

Comparison.--In _Loxia_ and _Spinus_, only one-third of the origin is
from the last free dorsal vertebra. In _Hesperiphona_, _Carpodacus_,
_Pinicola_, and _Leucosticte_, only one-fifth of the origin is from
this vertebra.


_+Musculus iliotibialis+_ (Fig. 1).--Broad and triangular, this muscle
covers most of the deeper muscles of the lateral aspect of the thigh.
The middle region is fused with the underlying _femorotibialis_
muscles. In the distal half of this muscle there are three distinct
parts; the anterior and posterior edges are fleshy and the central
part is aponeurotic. The origin is from a narrow line along the iliac
crests--from the origin of the _m. sartorius_, anteriorly, to the
origin of the _m. semitendinosus_ posteriorly. The origin is
aponeurotic in the preacetabular region but fleshy in the
postacetabular region. The distal part of the muscle is aponeurotic
and joins with the _femorotibialis_ muscles in the formation of the
patellar tendon. This tendon incloses the patella and inserts on a
line along the proximal edges of the cnemial crests of the
tibiotarsus.

Action.--Extends crus.

Comparison.--In _Vireo_ the central aponeurotic portion of this muscle
is absent.


_+Musculus femorotibialis externus+_ (Fig. 2).--Covering the lateral
and anterolateral surfaces of the femur, this large muscle has a
fleshy origin from the lateral edge of the proximal three-fourths of
the femur. The origin separates the insertion of the _m.
iliotrochantericus anticus_ from that of the _m. ischiofemoralis_ and,
in turn, is separated from the origin of the _m. femorotibialis
medius_ by the insertions of the _m. iliotrochantericus anticus_ and
_m. iliotrochantericus medius_. Approximately midway of the length of
the femur this muscle fuses anteromesially with the _m. femorotibialis
medius_. Distally, the _m. femorotibialis externus_ contributes to the
formation of the patellar tendon which inserts on a line along the
proximal edges of the cnemial crests of the tibiotarsus.

Action.--Extends crus.

Comparison.--No significant differences noted among the species studied.


_+Musculus femorotibialis medius+_ (Figs. 2, 4).--The origin of this
muscle, which lies along the anterior edge of the femur, is fleshy
from the entire length of the femur proximal to the level of
attachment of the proximal arm of the biceps loop. Laterally this
muscle is completely fused for most of its length with the _m.
femorotibialis externus_ and contributes to the formation of the
patellar tendon, which inserts on a line along the proximal edges of
the cnemial crests of the tibiotarsus. Many of the fibers,
nevertheless, insert on the proximal edge of the patella.

Action.--Extends crus.

Comparison.--No significant differences noted among the species
studied.


_+Musculus femorotibialis internus+_ (Fig. 4).--One of the most
superficial muscles lying on the medial surface of the thigh, this
muscle is divided, especially near the distal end, into two parts,
lateral and medial. The origin of the lateral part is fleshy from a
line on the medial surface of the femur; the origin begins proximally
at a point near the insertion of the _m. iliacus_. The medial, bulkier
part of the muscle has a fleshy origin on the medial surface of the
lower one-third of the femur. The two parts fuse to some extent above
the points of insertion and insert on the medial edge of the head of
the tibia.

Action.--Rotates tibia anteriorly.

Comparison.--Two parts of this muscle variously fused; otherwise, no
significant differences in the species studied.


_+Musculus piriformis+_ (Fig. 3).--This muscle is represented by the
_pars caudifemoralis_ only, the _pars iliofemoralis_ being absent in
passerine birds as far as is known. The _pars caudifemoralis_ is flat,
somewhat spindle-shaped, and passes anteroventrally from the pygostyle
to the femur. The origin is tendinous from the anteroventral edge of
the pygostyle, and the insertion is semitendinous on the
posterolateral surface of the shaft of the femur about one-fourth its
length from the proximal end.

Action.--Moves femur posteriorly and rotates it in this direction;
moves tail laterally and depresses it.

Comparison.--No significant differences noted among the species
studied.


_+Musculus semitendinosus+_ (Figs. 2, 3, 5).--The origin from the
extreme posterior edge of the posterior iliac crest of the ilium is
fleshy and is aponeurotic from the last vertebra of the synsacrum and
the transverse processes of several caudal vertebrae. The straplike
belly passes along the posterolateral margin of the thigh. Immediately
posterior to the knee, the muscle is divided transversely by a
ligament. That portion passing anteriorly from the ligament is the _m.
accessorius semitendinosi_ (here considered a part of the _m.
semitendinosus_) and is discussed below. The ligament continues
distally in two parts; one part inserts on the medial surface of the
_pars media_ of the _m. gastrocnemius_ and the other part fuses with
the tendon of insertion of the _m. semimembranosus_.

The _m. accessorius semitendinosi_ extends anteriorly from the above
mentioned ligament to a fleshy insertion on the posterolateral surface
of the femur immediately proximal to the condyles.

Action.--Moves femur posteriorly, flexes the crus and aids in
extending the tarsometatarsus.

Comparison.--No significant differences noted among the species
studied.


_+Musculus semimembranosus+_ (Figs. 3, 4, 5).--This straplike muscle
passes along the posteromedial surface of the thigh. The origin is
semitendinous along a line on the ischium, from a point dorsal to the
middle of the ischiopubic fenestra to the posterior end of the
ischium, and from a small area of the abdominal musculature posterior
to the ischium. The insertion is by means of a broad, thin tendon on a
ridge on the medial surface of the tibia immediately distal to the
head of this bone. The tendon of insertion passes between the head of
the _pars media_ and _pars interna_ of the _m. gastrocnemius_ and is
fused with the tendon of the _m. semitendinosus_.

Action.--Flexes crus.

Comparison.--No significant differences noted among the species
studied.


_+Musculus biceps femoris+_ (Fig. 2).--Long, thin, and somewhat
triangular, this muscle lies on the lateral side of the thigh just
underneath the _m. iliotibialis_. Its origin is from a line along the
anterior and posterior iliac crests underneath the origin of the _m.
iliotibialis_. Anterior to the acetabulum the origin is aponeurotic,
and the edge of this aponeurosis passes over the proximal end of the
femur. The origin posterior to the acetabulum is fleshy. The most
anterior point of origin is difficult to ascertain but it lies near
the center of the anterior iliac crest. The most posterior point of
origin is immediately dorsal to the posterior end of the ilioischiatic
fenestra. Behind the knee the fibers of this muscle converge to form
the strong tendon of insertion which passes through the biceps loop,
under the tendon of origin of the _m. flexor perforatus digiti II_,
and inserts on a small tubercle on the posterolateral edge of the
fibula at the point of the tibia-fibula fusion.

The biceps loop is tendinous and the distal end attaches to a
protuberance on the posterolateral edge of the femur at the proximal
edge of the external condyle. The proximal end attaches to the
anterolateral edge of the femur immediately proximal to the distal end
of the loop, which extends posterior to the femur. The distal arm of
this loop is connected with the tendon of origin of the _m. flexor
perforatus digiti II_ by a strong tendon.

Action.--Flexes crus.

Comparison.--No significant differences noted among the species
studied.


_+Musculus ischiofemoralis+_ (Fig. 3).--Short and thick, this muscle
arises directly from the lateral surface of the ischium between the
posterior iliac crest and the ischiopubic fenestra. The area of origin
extends to the posterior edge of the ischium. The insertion is
tendinous on the lateral surface of the trochanter opposite the
insertion of the _m. iliotrochantericus medius_.

Action.--Moves femur posteriorly and rotates it in this direction.

Comparison.--No significant differences noted among the species
studied.


_+Musculus obturator internus+_ (Figs. 4, 7).--Lying on the inside of
the pelvis and covering the medial surface of the ischiopubic
fenestra, is this flat, pinnate, leaf-shaped muscle. The origin is
fleshy and is from the ischium and pubis around the edges of this
fenestra; none of the fibers arises from the membrane stretched across
the fenestra. Anteriorly the fibers converge and form a strong tendon
that passes through the obturator foramen and inserts on the
posterolateral surface of the trochanter of the femur.

Action.--Rotates femur posteriorly.

Comparison.--No significant differences noted among the species
studied.


_+Musculus obturator externus+_ (Fig. 7).--Short and fleshy, this
muscle consists of two parts which are not easily separable but which
may be traced throughout its length. The parts are more nearly
distinct at the origin. The dorsal part arises directly from the
ischium along the dorsal edge of the obturator foramen. The larger
ventral part arises directly from the anterior and ventral edges of
the obturator foramen. The fibers of the dorsal part pass anteriorly,
cover the tendon of the _m. obturator internus_ laterally, and insert
on the trochanter around the point of insertion of the latter muscle.
The fibers of the ventral part pass parallel with the tendon of the
_m. obturator internus_ and insert on the trochanter immediately
distal and posterior to the tendon of the latter muscle.

Action.--Rotates femur posteriorly.

Comparison.--In _Passer_, _Estrilda_, _Poephila_, _Hesperiphona_,
_Carpodacus_, _Pinicola_, _Leucosticte_, _Spinus_ and _Loxia_, this
muscle is undivided and, in its position, origin, and insertion,
resembles the ventral part of the bipartite muscle described above.
The origin is from the anterior and ventral edges of the obturator
foramen and the insertion is on the trochanter of the femur
immediately distal and posterior to the insertion of the _m. obturator
internus_. In all other genera examined, the muscle is bipartite. In
_Chlorura_ the dorsal part is larger and better developed than it is
in the other genera.


_+Musculus adductor longus et brevis+_ (Figs. 3, 4, 5).--Consisting of
two distinct, straplike parts, this large muscle lies on the medial
surface of the thigh, posterior to the femur.

The _pars anticus_ has a semitendinous origin on a line that extends
posteriorly from the posteroventral edge of the obturator foramen to a
point half way across the membrane that covers the ischiopubic
fenestra. The insertion is fleshy along the posterior surface of the
femur from the level of the insertion of the _m. piriformis_ distally
to the medial surface of the internal condyle.

The _pars posticus_ originates by a broad, flat tendon on a line
across the posterior half of the membrane that covers the ischiopubic
fenestra. The insertion is at the point of origin of the _pars media_
of the _m. gastrocnemius_ on the posteromedial surface of the proximal
end of the internal condyle of the femur. There is a broad tendinous
connection with the proximal end of the _pars media_ of the _m.
gastrocnemius_. The anterior edge of the _pars posticus_ is overlapped
medially by the posterior edge of the _pars anticus_.

Action.--Flexes thigh; may flex crus also and may extend
tarsometatarsus.

Comparison.--In _Vireo olivaceous_, the origin of this muscle does not
extend the length of the ischiopubic fenestra. The origin,
furthermore, is along the dorsal edge of the ischiopubic fenestra and
not from the membrane covering the fenestra. Finally, in this species,
the origin of the _pars posticus_ is fleshy.


_+Musculus tibialis anticus+_ (Figs. 2, 5).--Lying along the anterior
edge of the crus, a part of this muscle is covered by the _m. peroneus
longus_. The origin is by two distinct heads, each of which is
pinnate. The anterior head arises directly from the edges of the outer
and inner cnemial crests. The posterior head arises by a short, strong
tendon from a small pit on the anterodistal edge of the external
condyle of the femur. This tendon and the proximal end of the muscle
pass between the head of the fibula and the outer cnemial crest. The
two heads of the muscle fuse at a place slightly more than one-half of
the distance down the crus. At the distal end of the crus this muscle
gives rise to a strong tendon which passes under a fibrous loop
immediately proximal to the external condyle in company with the _m.
extensor digitorum longus_ and which passes between the condyles of
the tibia and inserts on a tubercle on the anteromedial edge of the
proximal end of the tarsometatarsus.

Action.--Flexes tarsometatarsus.

Comparison.--No significant differences noted among the species
studied.


_+Musculus extensor digitorum longus+_ (Figs. 3, 5, 8).--Slender and
pinnate, this muscle lies along the anteromedial surface of the tibia.
The origin is fleshy from most of the region between the cnemial
crests and from a line along the anterior surface of the proximal
fourth of the tibia. Approximately two-thirds of the distance down the
crus the muscle gives rise to the tendon of insertion which passes
through the fibrous loop near the distal end of the tibia in company
with the _m. tibialis anticus_. The tendon then passes along beneath
the supratendinal bridge at the distal end of the tibia, traverses the
anterior intercondylar fossa, and passes beneath a bony bridge on the
anteromedial surface of the proximal end of the tarsometatarsus. The
tendon continues along the anterior surface of the tarsometatarsus to
a point immediately above the bases of the toes and there gives rise
to three branches, one to the anterior surface of each foretoe. The
insertions of each branch are on the anterior surfaces of the
phalanges as shown in Fig. 8.

Action.--Extends foretoes.

Comparison.--This muscle is weakly developed in _Leucosticte_ and
_Calvarius_; the belly is slender and extends only half way down the
crus before giving rise to the tendon of insertion. The functional
significance of this variation is difficult to understand. The
convergence in muscle pattern shown by these two genera, however, is
in all probability the result of similarities in behavior patterns.
These birds perch less frequently than do the other birds studied.
Thus, the toes are neither flexed nor extended as often; the smaller
size of the _m. extensor digitorum longus_ may have resulted in part
from this lessened activity. Except for the variations just noted,
there are no significant differences among the species studied; even
the rather complex patterns of insertion are identical.


_+Musculus peroneus longus+_ (Fig. 1).--Relatively thin and straplike,
this muscle lies on the anterolateral surface of the crus and is
intimately attached to the underlying muscles. The part of the origin
from the proximal edges of the inner and outer cnemial crests is
semitendinous but the part of the origin from the lateral edge of the
shaft of the fibula is tendinous. Approximately two-thirds the
distance down the crus the muscle gives rise to the tendon of
insertion. Immediately above the external condyle of the tibiotarsus
this tendon divides. The posterior branch inserts on the proximal end
of the lateral edge of the tibial cartilage. The anterior branch
passes over the lateral surface of the external condyle to the
posterior surface of the tarsometatarsus and there unites with the
tendon of the _m. flexor perforatus digiti III_.

Action.--Extends tarsometatarsus and flexes third digit.

Comparison.--No significant differences noted among the species
studied.


_+Musculus peroneus brevis+_ (Figs. 2, 3).--Lying along the
anterolateral surface of the tibia, this slender, pinnate muscle
arises from a fleshy origin along this surface and along the anterior
surface of the fibula from a point immediately proximal to the
insertion of the _m. biceps femoris_ to a point approximately
two-thirds of the way down the crus. Near the distal end of the tibia
the muscle gives rise to the tendon of insertion that passes through a
groove on the anterolateral edge of the tibia just above the external
condyle. Here the tendon is held in place by a broad fibrous loop and
passes under the anterior branch of the tendon of insertion of the _m.
peroneus longus_ and inserts on a prominence on the lateral edge of
the proximal end of the tarsometatarsus.

Action.--Extends tarsometatarsus and may abduct it slightly.

Comparison.--No significant differences noted among the species
studied.


_+Musculus gastrocnemius+_ (Figs. 1, 4).--The largest muscle of the
pelvic appendage, it covers superficially all of the posterior
surface, most of the medial surface, and half of the lateral surface
of the crus. The muscle originates by three distinct heads.

The _pars externa_ covers the posterolateral surface of the crus, is
intermediate in size between the other two heads, and arises by a
short, strong tendon from a small bony protuberance on the
posterolateral side of the distal end of the femur immediately
proximal to the fibular condyle. The tendon is intimately connected
with the distal arm of the loop for the _m. biceps femoris_.

The _pars media_ is the smallest of the three heads and lies on the
medial surface of the crus. The head of the _pars media_ is separated
from the _pars interna_ by the tendon of insertion of the _m.
semimembranosus_ and originates by a short, strong tendon from the
posteromedial surface of the proximal end of the internal condyle of
the femur. The proximal portion of the _pars media_ has tendinous
connections with the tendon of the _m. semitendinosus_ and with the
_pars posticus_ of the _m. adductor longus et brevis_.

The _pars interna_ is the largest of the three heads and covers most
of the medial surface of the crus. This head in its proximal portion
is distinctly divided into anterior and posterior parts, the former
overlapping the latter medially. The origin of the posterior part is
fleshy from the anterior half of the tibial head. Some of the fibers
of the anterior part arise directly from the inner cnemial crest while
its remaining fibers arise from the patellar tendon (Fig. 1) and form
a band that extends around the anterior surface of the knee, covering
the insertion of the _m. sartorius_.

Approximately half way down the crus, the three heads give rise to the
tendon of insertion, the _tendo achillis_, which passes over and is
tightly bound to the posterior surface of the tibial cartilage. The
insertion is tendinous on the posterior surface of the hypotarsus and
along the posterolateral ridge of the tarsometatarsus. This tendon
seems to be continuous with a fascia which forms a sheath around the
posterior surface of the tarsometatarsus holding the other tendons of
this region firmly in the posterior sulcus.

Action.--Extends tarsometatarsus.

Comparison.--Study of the _pars externa_ and _pars media_ reveals no
significant differences among the species dissected. The _pars
interna_, however, is subject to some variation which is described
below.

       _Pars interna_ bipartite

  _Vireo_              _Chlorura_
  _Seiurus_            _Pipilo_
  _Icterus_            _Calamospiza_
  _Molothrus_          _Chondestes_
  _Piranga_            _Junco_
  _Richmondena_        _Spizella_
  _Guiraca_            _Zonotrichia_
  _Passerina_          _Passerella_
  _Spiza_              _Calcarius_

The two parts of the _m. gastrocnemius_ are most distinct in _Vireo_.
_Icterus_, _Molothrus_, _Richmondena_, _Guiraca_, and _Passerina_ lack
the fibrous band that passes around the front of the knee. In _Spiza_
this band of fibers is smaller than in the other species.

     _Pars interna_ undivided

  _Passer_            _Pinicola_
  _Estrilda_          _Leucosticte_
  _Poephila_          _Spinus_
  _Hesperiphona_      _Loxia_
  _Carpodacus_

In _Leucosticte_, although the _pars interna_ is undivided, there is a
band of fibers which extends around the front of the knee (see
discussion, p. 183).


_+Musculus plantaris+_ (Fig. 5).--Small and slender, this muscle lies
on the posteromedial surface of the crus, beneath the _pars interna_
of the _m. gastrocnemius_ and originates by fleshy fibers from the
posteromedial surface of the proximal end of the tibia immediately
distal to the internal articular surface. The belly extends
approximately one-sixth of the way down the crus and gives rise to a
long, slender tendon that inserts on the proximomedial edge of the
tibial cartilage.

Action.--Extends tarsometatarsus.

Comparison.--No significant differences noted among the species
studied.


_+Musculus flexor perforatus digiti II+_ (Figs. 3, 9).--This is a
slender muscle which lies on the lateral side of the crus beneath the
_pars externa_ of the _m. gastrocnemius_ and is intimately connected
anteromedially with the _m. flexor digitorum longus_ and
posteromedially with the _m. flexor hallucis longus_. The origin is by
a strong tendon from the lateral surface of the external condyle of
the femur at the point of origin of the _m. flexor perforans et
perforatus digiti II_. This tendon serves also as the origin of the
anterior head of the _m. flexor hallucis longus_. The tendon connects
also by a broad tendinous band with the distal arm of the loop for the
_m. biceps femoris_ and by a similar band with the lateral edge of the
fibula immediately distal to the head. The tendon of insertion passes
distally, perforates the tibial cartilage near its lateral edge,
traverses the middle medial canal of the hypotarsus (Fig. 6), and
passes distally to the foot. At the distal end of the tarsometatarsus
the tendon is held against the medial surface of the first metatarsal
by a straplike sheath. The tendon then passes over a sesamoid bone
between the first metatarsal and the base of the second digit and is
bound to this bone by a sheath. The tendon inserts mainly along the
posteromedial edge of the proximal end of the first phalanx of the
second digit, although the termination is sheathlike and covers the
entire posterior surface of this phalanx. This sheathlike termination
is perforated by the tendons of the _m. flexor perforans et perforatus
digiti II_ and the branch of the _m. flexor digitorum longus_ that
inserts on the second digit.

Action.--Flexes second digit.

Comparison.--In _Vireo_ this muscle is larger and more deeply situated
than it is in the other species examined and has no connection with
the _m. flexor hallucis longus_.


_+Musculus flexor perforatus digiti III+_ (Fig. 5).--Long and
flattened, this muscle lies on the posteromedial side of the crus
beneath the _m. gastrocnemius_. The belly is tightly fused laterally
with the belly of the _m. flexor hallucis longus_ and posteriorly with
the belly of the _m. flexor perforatus digiti IV_. The origin is by a
long, strong tendon from a small tubercle just medial to, and at the
proximal end of, the external condyle of the femur. Below the middle
of the crus this muscle terminates in a strong tendon which perforates
the tibial cartilage near its lateral edge. In this region the tendon
is sheathlike and wrapped around the tendon of the _m. flexor
perforatus digiti IV_. These two tendons together pass through the
posterolateral canal of the hypotarsus (Fig. 6). Immediately distal to
the hypotarsus the two tendons separate, and the tendon of the _m.
flexor perforatus digiti III_ receives a branch of the tendon of the
_m. peroneus longus_. The tendon passes distally over the surface of
the second trochlea, and its insertion is sheathlike on the posterior
surface of the first phalanx, and on the proximal end of the second.
In the area of insertion this tendon is perforated by that of the _m.
flexor perforans et perforatus digiti III_ and by that of the _m.
flexor digitorum longus_ to the third digit.

Action.--Flexes digit III.

Comparison.--In _Passer_, _Estrilda_, _Poephila_, _Hesperiphona_,
_Carpodacus_, _Pinicola_, _Leucosticte_, _Spinus_, and _Loxia_ the
edges of the sheathlike tendon are thickened at the points of
insertion, so that the tendon appears to have two branches which
insert along the posterolateral edges of the first phalanx and are
connected medially by a fascia.


_+Musculus flexor perforatus digiti IV+_ (Fig. 3).--Extending along
the posterior edge of the crus, this slender muscle lies beneath the
_m. gastrocnemius_. The belly is fused with those of the _m. flexor
hallucis longus_ and _m. flexor perforatus digiti III_. Its origin is
fleshy from the intercondyloid region of the distal end of the femur
and has a few fibers arising from the tendon of origin of the _m.
flexor perforatus digiti III_. Near the distal end of the crus the
muscle gives rise to the strong tendon of insertion which perforates
the tibial cartilage near its lateral edge and in this region is
ensheathed by the tendon of the _m. flexor perforatus digiti III_. The
two tendons pass together through the posterolateral canal of the
hypotarsus (Fig. 6). The tendon continues distally along the
tarsometatarsus and the posterior surface of digit IV. The tendon
bifurcates at approximately the middle of the first phalanx. A short
lateral branch inserts on the posterolateral edge of the proximal end
of the second phalanx. The long medial branch is perforated by a
branch of the _m. flexor digitorum longus_; the distal end is
flattened, has thickened edges, and inserts over the posterior
surfaces of the distal end of the second phalanx, and over the
proximal end of the third phalanx.

Action.--Flexes digit IV.

Comparison.--No significant differences noted among the species
studied.


_+Musculus flexor perforans et perforatus digiti II+_ (Figs. 2,
9).--Small and spindle-shaped, this muscle lies on the posterolateral
side of the crus immediately beneath the _pars externa_ of the _m.
gastrocnemius_. The origin is fleshy and arises in company with the
_m. flexor perforans et perforatus digiti III_ from a point on the
posterolateral surface of the distal end of the femur between the
point of origin of the _pars externa_ of the _m. gastrocnemius_ and
the fibular condyle. The belly extends approximately one-fourth of the
way down the crus and gives rise to the tendon of insertion which
passes distally and superficially through the posterior edge of the
tibial cartilage. The tendon traverses the posteromedial canal of the
hypotarsus (Fig. 6) and continues along the posterior surface of the
tarsometatarsus. Between the first metatarsal and the base of the
second digit the tendon is enclosed by the medial surface of a
sesamoid bone. This tendon then perforates that of the _m. flexor
perforatus digiti II_ at the level of the first phalanx and in turn is
perforated by the tendon of the _m. flexor digitorum longus_ at the
proximal end of the second phalanx. The insertion is on the posterior
surface of the second phalanx.

Action.--Flexes digit II.

Comparison.--In _Passer_, _Estrilda_, _Poephila_, _Hesperiphona_,
_Carpodacus_, _Pinicola_, _Leucosticte_, _Spinus_, and _Loxia_ the
proximal portion of this muscle is more intimately connected with the
posterior edge of the _m. flexor perforans et perforatus digiti III_
than it is in the other species examined.


_+Musculus flexor perforans et perforatus digiti III+_ (Fig. 2).--Long
and pinnate, this muscle lies on the lateral surface of the crus
beneath the _m. peroneus longus_ and _pars externa_ of the _m.
gastrocnemius_. There are two distinct heads. The origin of the
anterior head is fleshy from the proximal edge of the outer cnemial
crest and from the internal edge of the distal end of the patellar
tendon. The posterior head arises by a tendon from the femur in
company with the _m. flexor perforans et perforatus digiti II_, is
connected also with the tendon of origin of the _m. flexor perforatus
digiti II_, and is loosely attached to the head of the fibula. Fibers
from the belly of the muscle attach throughout its length to the
lateral edge of the fibula, and the muscle is tightly fused also with
adjacent muscles. The tendon of insertion is formed approximately
one-half the way down the crus. The tendon perforates the posterior
surface of the tibial cartilage and passes through the posteromedial
canal of the hypotarsus (Fig. 6). At the base of the third digit the
tendon ensheathes that of the _m. flexor digitorum longus_ and the two
together perforate the tendon of the _m. flexor perforatus digiti
III_. Immediately distal to this perforation the tendon of the _m.
flexor perforans et perforatus digiti III_ ceases to ensheath that of
the _m. flexor digitorum longus_. The latter passes beneath that of
the former. Near the distal end of the second phalanx the tendon of
the _m. flexor digitorum longus_ perforates that of the _m. flexor
perforans et perforatus digiti III_. The latter inserts on the
posterior surface of the distal end of the second phalanx and the
proximal end of the third.

Action.--Flexes digit III.

Comparison.--In _Passer_, _Estrilda_, and _Poephila_, and in all the
cardueline finches examined the proximal portion of this muscle is
more intimately connected with the anterior edge of the _m. flexor
perforans et perforatus digiti II_ than it is in the other species
examined.


_+Musculus flexor digitorum longus+_ (Figs. 3, 5).--This strong,
pinnate muscle is deeply situated along the posterior surfaces of the
tibia and fibula. There are two distinct heads of origin. The lateral
head arises by means of fleshy fibers from the posterior edge of the
head of the fibula. The medial head arises by means of fleshy fibers
from the region under the ledgelike external and internal articular
surfaces of the proximal end of the tibia. Neither head has any
connection with the femur in contrast to the condition, described by
Hudson (1937: 46-47) in the crow, _Corvus brachyrhynchos_, and in the
raven, _Corvus corax_. Near the point of insertion of the _m. biceps
femoris_ the two heads fuse. The common belly is attached by fleshy
fibers to the posterior surface of the tibia and fibula for two-thirds
of the distance down the crus. Near the distal end of the crus the
muscle terminates in a strong tendon which passes deeply through the
tibial cartilage and traverses the anteromedial canal of the
hypotarsus (Fig. 6). About midway down the tarsometatarsus this tendon
becomes ossified. Immediately above the bases of the toes it gives
rise to three branches, one to the posterior surface of each of the
foretoes. These branches perforate the other flexor muscles of the
toes as described in the accounts of those muscles and insert as
follows: The branch to digit II inserts on the base of the ungual
phalanx and by a stout, tendinous slip on the distal end of the second
phalanx (Fig. 9). The branch to digit III inserts on the base of the
distal end of the third phalanx and a stronger slip to the distal end
of the second or proximal end of the third. The branch to digit IV
inserts on the base of the ungual phalanx, with one tendinous slip to
the distal end of the third phalanx and another to the distal end of
the fourth.

Action.--Flexes foretoes.

Comparison.--No significant differences noted among the species
studied.


_+Musculus flexor hallucis longus+_ (Fig. 3).--Situated immediately
posterior to the _m. flexor digitorum longus_, the belly of this
large, pinnate muscle is intimately connected anteriorly to that of
the _m. flexor perforatus digiti II_. The _m. flexor hallucis longus_
arises by two heads which are separated by the tendon of insertion of
the _m. biceps femoris_. The smaller anterior head arises from the
same tendon as does the _m. flexor perforatus digiti II_. The larger
posterior head arises by means of fleshy fibers from the
intercondyloid region of the posterior surface of the femur along with
the _m. flexor perforatus digiti III_ and _IV_. The two heads join
just distal to the point of insertion of the _m. biceps femoris_.
There is no trace of a tendinous band connecting the two heads as
there is in the crow and in the raven (Hudson, 1937:49). Near the
distal end of the shank the muscle gives rise to a strong tendon which
perforates the tibial cartilage along its lateral edge and passes
through the anterolateral canal of the hypotarsus (Fig. 6). The tendon
crosses over to the medial surface of the tarsometatarsus, passes
distally, and perforates the sheathlike tendon of the _m. flexor
hallucis brevis_ between the first metatarsal and the trochlea for
digit II. The tendon continues along the posterior surface of the
hallux and has a double insertion; the main tendon attaches to the
base of the ungual phalanx and a smaller branch inserts on the distal
end of the proximal phalanx.

Action.--Flexes hallux.

Comparison.--In _Vireo_ this muscle has only the posterior head of
origin and is not connected with the _m. flexor perforatus digiti II_.
The muscle is proportionately smaller and weaker than in any of the
other species studied.


_+Musculus extensor hallucis longus+_ (Fig. 4).--One of the smallest
muscles of the leg, the origin is fleshy from the anteromedial edge of
the proximal end of the tarsometatarsus. The belly is long and slender
and terminates distally in a slender tendon which passes distally
along the posterior surfaces of the first metatarsal and the first
digit. The insertion is on the base of the ungual phalanx. Near the
distal end of the proximal phalanx, the tendon passes between two
thick bands of fibro-elastic tissue which insert also on the ungual
phalanx. These bands of tissue function as automatic extensors of the
claw.

Action.--Extends hallux; action must be slight.

Comparison.--In _Vireo_ this muscle is proportionately larger and
better developed than it is in any of the other species examined.


_+Musculus flexor hallucis brevis+_ (Fig. 4).--This minute muscle has
a fleshy origin from the medial surface of the hypotarsus. The short
belly terminates in a weak, slender tendon which passes down the
posteromedial surface of the tarsometatarsus and into the space
between the first metatarsal and the trochlea for digit II. In this
region the tendon envelops the tendon of the _m. flexor hallucis
longus_ and inserts on the distal end of the first metatarsal and on
the proximal end of the first phalanx of the first digit.

Action.--Flexes hallux; action must be slight.

Comparison.--The small size of this muscle makes it exceedingly
difficult to study. The muscle is larger in _Vireo_ than in any of the
other species examined. This may be correlated with the smaller size
of the _m. flexor hallucis longus_ in this species. The muscle does
not seem to be so well developed in the cardueline finches as it is in
the other species.


_+Musculus abductor digiti IV+_ (Fig. 2).--Extremely small, delicate
and difficult to demonstrate, this muscle arises in a fleshy origin
immediately from underneath the posterior edge of the external cotyla
of the tarsometatarsus. The tendon of insertion is long and slender
and inserts along the lateral edge of the first phalanx of digit IV.

Action.--Abducts digit IV.

Comparison.--No significant differences noted among the species
studied.


_+Musculus lumbricalis.+_--Semitendinous throughout its length, this
muscle arises from the ossified tendon of the _m. flexor digitorum
longus_ at a point immediately proximal to the branching of this
tendon. The insertion is on the joint pulleys and capsules at the base
of the third and fourth digits.

Action.--Hudson (1937:57) states that: "Meckel (_vide_ Gadow--1891, p.
204) considered this muscle as serving to draw the joint pulley behind
in order to protect it from pinching during the bending of the toes.
It perhaps also tends to flex the third and fourth digits."

Comparison.--No significant differences noted among the species
studied.


Discussion of the Myological Investigations

Simpson (1944:12) and others have emphasized that different parts of
organisms evolve at different rates. Beecher (1951b:275) in stating
that "... the hind limb is very similar in muscle pattern throughout
the Order Passeriformes and seems to have become relatively static
after attaining a high level of general efficiency ..." implies that
the muscle pattern of the leg must be one of long standing and slow
change. This concept was emphasized by Hudson (1937) who found but
little variation in muscle pattern among members of the several
families of passerine birds. The concept is further confirmed by the
present investigation. The intricate patterns of origin and of
insertion seem to remain almost the same throughout the order in spite
of adaptive radiation which has occurred.

Two major differences in patterns of leg-musculature, however, were
found among the species studied, and these differences are significant
since they are consistent between subfamilies. The muscles involved
are the _m. obturator externus_ and the _pars interna_ of the _m.
gastrocnemius_.

The _m. obturator externus_ is bipartite, consisting of dorsal and
ventral parts, in the passerine species studied by Hudson (1937) and
in all of the species examined by me except the ploceids and the
cardueline finches. In the ploceids and cardueline finches this muscle
is undivided and resembles in its position, origin, and insertion only
the ventral portion of the muscle found in the other birds studied. It
is difficult to imagine what advantage or disadvantage might be
associated with the bipartite or with the undivided condition. The
action of this muscle is to rotate the femur (right femur clockwise,
left femur counterclockwise), and certainly the greater mass of the
bipartite muscle could lend greater strength to such action. The
possible significance of this is discussed below.

     List of Abbreviations Used in Figures

  Abd. dig. IV         _M. abductor digiti IV_
  Acc.                 _M. accessorius semitendinosi_
  Add. long.           _M. adductor longus et brevis_
  Anterolat. can.      Anterolateral canal of hypotarsus
  Anteromed. can.      Anteromedial canal of hypotarsus
  Bic. fem.            _M. biceps femoris_
  Bic. loop            Loop for _m. biceps femoris_
  Ext. cot.            External cotyla
  Ext. dig. l.         _M. extensor digitorum longus_
  Ext. hal. l.         _M. extensor hallucis longus_
  Fem. tib. ext.       _M. femorotibialis externus_
  Fem. tib. int.       _M. femorotibialis internus_
  Fem. tib. med.       _M. femorotibialis medius_
  F. dig. l.           _M. flexor digitorum longus_
  F. hal. brev.        _M. flexor hallucis brevis_
  F. hal. l.           _M. flexor hallucis longus_
  F. p. et p. d. II    _M. flexor perforans et perforatus digiti II_
  F. p. et p. d. III   _M. flexor perforans et perforatus digiti III_
  F. per. d. II        _M. flexor perforatus digiti II_
  F. per. d. III       _M. flexor perforatus digiti III_
  F. per. d. IV        _M. flexor perforatus digiti IV_
  Gas.                 _M. gastrocnemius_
  Iliacus              _M. iliacus_
  Il. tib.             _M. iliotibialis_
  Il. troc. ant.       _M. iliotrochantericus anticus_
  Il. troc. med.       _M. iliotrochantericus medius_
  Il. troc. post.      _M. iliotrochantericus posticus_
  Int. cot.            Internal cotyla
  Isch. fem.           _M. ischiofemoralis_
  Midmed. can.         Midmedial canal of hypotarsus
  Obt. ext.            _M. obturator externus_
  Obt. int.            _M. obturator internus_
  P. ant.              _Pars anticus_
  P. ext.              _Pars externa_
  P. int.              _Pars interna_
  P. med.              _Pars media_
  P. post.             _Pars posticus_
  Per. brev.           _M. peroneus brevis_
  Per. long.           _M. peroneus longus_
  Pirif.               _M. piriformis_
  Plan.                _M. plantaris_
  Posterolat. can.     Posterolateral canal of hypotarsus
  Posteromed. can.     Posteromedial canal of hypotarsus
  Sar.                 _M. sartorius_
  Semim.               _M. semimembranosus_
  Semit.               _M. semitendinosus_
  Tib. ant.            _M. tibialis anticus_
  Tib. cart.           Tibial cartilage

  [Illustration: FIG. 1. _Pipilo erythrophthalmus._ Lateral view of
      the superficial muscles of the left leg, x 1.5.]

  [Illustration: FIG. 2. _Pipilo erythrophthalmus._ Lateral view of
      the left leg showing a deeper set of muscles. The superficial
      muscles _iliotibialis_, _sartorius_, _gastrocnemius_ and
      _peroneus longus_ have been removed, x 1.5.]

  [Illustration: FIG. 3. _Pipilo erythrophthalmus._ Lateral view of
      the left leg showing the still deeper muscles. In addition to
      those listed for figure 2, the following muscles have been
      wholly or partly removed: _iliotrochantericus posticus_,
      _femorotibialis externus_, _femorotibialis medius_,
      _biceps femoris_, _semitendinosus_, _tibialis anticus_,
      _flexor perforans et perforatus digiti II_, and _flexor
      perforans et perforatus digiti III_, x 1.5.]

  [Illustration: FIG. 4. _Pipilo erythrophthalmus._ Medial view of
      the superficial muscles of the left leg, x 1.5.]

  [Illustration: FIG. 5. _Pipilo erythrophthalmus._ Medial view of
      the left leg showing a deeper set of muscles than those seen
      in figure 4. The following superficial muscles have been
      removed: _iliotibialis_, _sartorius_, _femorotibialis internus_,
      _obturator internus_, _adductor longus (pars posticus)_,
      _gastrocnemius_, and _peroneus longus_, x 1.5.]

  [Illustration: FIG. 6. _Pipilo erythrophthalmus._ Proximal end of
      left tarsometatarsus and the hypotarsus, x 4.]

  [Illustration: FIG. 7. _Pipilo erythrophthalmus._ Lateral view of
      proximal end of left femur and a portion of the pelvis, x 3.5.]

  [Illustration: FIG. 8. _Pipilo erythrophthalmus._ Upper surfaces
  of the phalanges of the foretoes of the left foot showing
  insertions of the _M. extensor digitorum longus_, x 3.]

  [Illustration: FIG. 9. _Pipilo erythrophthalmus._ Medial view of
      the second digit of the left foot, showing insertions of the
      flexor muscles, x 3.]

The division of the _pars interna_ of the _m. gastrocnemius_ into
anterior and posterior parts has not been reported by previous authors
yet the division is quite distinct in those birds in which it occurs.
Hudson (1937:36) points out that in some non-passerine birds the _pars
interna_ is double, but that in these species the _m. semimembranosus_
inserts between the two parts. This is not the condition in those
species studied by me. Only the ploceids and the cardueline finches in
the present investigation fail to show such a division. The undivided
muscle in these birds resembles, in its origin and position, the
posterior portion of the muscle found in those species showing the
bipartite condition. The greater mass of the bipartite muscle probably
makes possible a stronger extension of the tarsometatarsus.

Thus, the divided or undivided conditions of the _m. obturator
externus_ and the _pars interna_ of the _m. gastrocnemius_ seem to be
correlated with the degrees of strength of certain movements of the
leg. It is conceivable that these differences in structure are
correlated with the manner in which food is obtained, the birds having
the bipartite muscles being those which spend the most time on the
ground searching and scratching for seeds and other sorts of food.
Yet, in _Leucosticte_, a cardueline, and in _Calcarius_, an
emberizine, whose foraging habits are rather similar, the structure is
unlike. _Leucosticte_ does resemble the emberizines and also _Piranga_
and _Spzia_ in the extension of a band of muscle fibers from the _pars
interna_ of the _m. gastrocnemius_ around the front of the knee. A
band of muscle fibers of this sort strengthens the knee joint and
gives still more strength to the _pars interna_. This condition has
been reported in a number of birds by Hudson (1937) and is, in all
probability, an adaptation for greater strength of certain leg
movements. The development of this band in _Leucosticte_ seems to
parallel that in the other birds studied and does not indicate
relationship, since in _Leucosticte_ this band arises from the
undivided muscle which (as stated above) resembles only the posterior
portion of the bipartite muscle described for the other birds. In the
latter, the muscular band arises from the anterior part of the muscle.

Minor differences in muscle pattern, like those already mentioned, are
consistent also between subfamilies, but correlation of these minor
differences with function is difficult. There is the implication,
however, that in all the groups except the carduelines and ploceids,
the emphasis is on greater strength and mobility of the leg. In the
carduelines that were studied the origin of the _m. sartorius_ does
not extend so far craniad as in the other species. In the latter, at
least half of the origin is from the last one or two free dorsal
vertebrae; in the carduelines no more than one third of the origin is
anterior to the ilium. It is conceivable that the more craniad the
origin, the stronger the forward movement of the thigh would be.

In _Passer_, _Estrilda_ and _Poephila_, and in all the cardueline
finches examined, the bellies of the _m. flexor perforans et
perforatus digiti II_ and the _m. flexor perforans et perforatus
digiti III_ are more intimately connected than they are in the other
species studied. Thus, the amount of independent action of these
muscles in _Passer_, in the estrildines, and in the carduelines
probably is reduced.

In _Passer_, the estrildines, and the carduelines the edges of the
sheathlike tendon of insertion of the _m. perforatus digiti III_ are
thickened; as a result the insertion appears superficially to be
double but closer examination reveals that there is a fascia stretched
between the thickened edges. In the other species examined, the
insertion is sheathlike throughout and there are no thick areas. I
cannot explain this on the basis of function. The difference, however,
is obvious and constant.

Aside from the differences noted above, there were variations of
muscle pattern that seem to be significant only in _Vireo olivaceus_.
In this species the central, aponeurotic portion of the _m.
iliotibialis_ is absent. The origin of the _m. adductor longus et
brevis_ is from the dorsal edge of the ischiopubic fenestra and not
from the membrane covering this fenestra. The origin of the _pars
posticus_ of this muscle, furthermore, is fleshy and not tendinous as
it is in the other species. The _m. flexor perforatus digiti II_ is
larger and more deeply situated in _Vireo_ and has, furthermore, no
connection with the _m. flexor hallucis longus_. The latter muscle is
smaller and weaker than in any of the other species and has only one
(the posterior) head of origin. The _m. flexor hallucis brevis_, on
the contrary, is larger than in the other birds, compensating,
probably, for the small _m. flexor hallucis longus_. In those
differences, however, which separate the carduelines and ploceids from
the other birds studied, _Vireo_ resembles, in every instance, the
richmondenines, emberizines, tanagers, warblers, and blackbirds.

On the basis of differences in leg-musculature the species which are
now included in the Family Fringillidae may be separated into two
groups. One group includes the richmondenines and the emberizines; the
other, the carduelines. The muscle patterns of the legs of the birds
of the first group are indistinguishable from those of _Seiurus_,
_Icterus_, _Molothrus_, and _Piranga_, and except for the differences
noted are similar to those in _Vireo_. The carduelines, on the other
hand, are similar in every point of leg-musculature to the ploceids
which were studied. Thus, the heterogeneity of the Family
Fringillidae, as now recognized, is emphasized by differences in the
muscle patterns of the leg.




COMPARATIVE SEROLOGY


General Statement

The application of serological techniques to the problems of animal
relationships has been attempted with varying degrees of success over
a period of approximately fifty years. Few of the earlier studies were
of a quantitative nature, but within the past decade, satisfactory
quantitative serological techniques have been developed whereby
taxonomic relationships may be estimated. The usefulness of
comparative serology in taxonomy has been demonstrated in
investigations of many groups wherein results obtained have, in most
instances, been compatible with the results obtained by more
conventional methods, such as comparative morphology. As Boyden
(1942:141) stated, "comparative serology ... is no simple guide to
animal relationship." However, the objectiveness of its methods, the
fact that it has its basis in the comparisons of biochemical systems
which seem to be relatively slow to change in response to external
environmental influences, and the fact that the results are of
quantitative nature favor, where possible, the inclusion of data from
comparative serology along with that from more conventional sources
when an attempt is made to determine the relationships of groups of
animals.

The application of serological methods in ornithology has not been
extensive. Irwin and Cole (1936) and Cumley and Irwin (1941, 1944)
used two species of doves and their hybrids and demonstrated that a
distinction between the red cells of these birds could be made by use
of immunological methods involving the agglutinin reaction. McGibbon
(1945) was able to distinguish the red cells of interspecific hybrids
in ducks by similar methods. Irwin (1953) used similar techniques in
his study of the evolutionary patterns of some antigenic substances of
the blood cells of birds of the Family Columbidae. Sasaki (1928)
demonstrated the usefulness of the precipitin technique in
distinguishing species of ducks and their hybrids. This technique
was used successfully also by DeFalco (1942) and by Martin and
Leone (1952). Working with groups of known relationships, these
investigators showed that the "accepted" systematic positions of
certain birds were confirmed by serological procedures. The precipitin
reaction, however, has never been applied to actual problems in avian
taxonomy prior to the present study.


Preparation of Antigens

Although most previous work in comparative serology in which
precipitin tests were used has involved the use of whole sera as
antigens, Martin and Leone (1952) indicated that tissue extracts are
satisfactory as antigens and that serological differentiation can be
obtained with these extracts and the antisera to them. I decided,
therefore, to use such extracts in these investigations, since the
small sizes of the birds to be tested made it impracticable to obtain
enough whole sera.

Most of the birds used were obtained by shooting, but a few were
trapped and the exotic species were purchased alive from a pet dealer.
When a bird was killed, the entire digestive tract was carefully
removed to prevent the escape of digestive enzymes into the tissues
and to prevent putrefaction by action of intestinal bacteria. As soon
as possible (and within three hours in every instance) the bird was
skinned, the head, wings, and legs were removed, and the body was
frozen. Each specimen, consisting of trunk, heart, lungs, and kidneys,
was wrapped separately and carefully in aluminum foil to prevent
dehydration of the tissues. The specimens were kept frozen until the
time when the extracts were made.

When an extract was to be prepared, the specimen was allowed to thaw
but not to become warm. In the cold room with the temperature of all
equipment and reagents at 2 deg.C., the specimen was placed in a Waring
blender with 0.9 per cent aqueous solution of NaCl buffered with M/150
K_{2}HPO_{4} and M/150 Na_{2}HPO_{4} to a pH of 7.0. The amount of
reagent used was 75 ml. of saline for each gram of tissue to be
extracted. The tissues were minced in the blender, allowed to stand at
2 deg.C. for 72 hours, and the tissue residues removed by centrifugation
in a refrigerated centrifuge. Formalin was added to a portion of the
supernatant in the amount necessary to make the final dilution 0.4 per
cent. This formolization was found to be necessary to inhibit the
action of autolytic enzymes over the period of time required to
complete the investigations. The effects of formolization on the
antigenicity and reactivity of proteins are discussed later. It was
necessary to sterilize and clarify the "native" (unformolized)
extracts; this was done by filtration through a Seitz filter. These
"native" substances were used only in the early stages of the
investigation (see below). The filtrate was bottled and stored at 2 deg.C.
In the early stages of this investigation clarification of the
formolized extract was accomplished by the same sort of filtration. It
was determined, however, that centrifugation in a refrigerated
centrifuge at high speeds (17,000g) served the same purpose and was
quicker. The formolized extracts were bottled and also stored at 2 deg.C.
(although refrigerated storage of the formolized extracts does not
seem necessary). For each extract the amount of protein present was
determined colorimetrically by the method of Greenberg (1929) with a
Leitz Photrometer.

Species for which extracts were prepared and the protein values of the
extracts are listed in Table 1. Extracts of some species were used
throughout most of the experiment; extracts of others were used only
when needed for purposes of comparison.

  TABLE 1.--Species from Which Extracts Were Prepared and Injection
     Schedules for Extracts Against Which Antisera Were Produced

 ==========================+==========+=================================
                           | Protein, |
           SPECIES         | gms. per |      Injection schedules for
                           | 100 ml.  |      production of antisera
 --------------------------+----------+---------------------------------
 _Myiarchus crinitus_      |   0.65   | Series 1: Intravenous, 0.5, 1.0,
      (Linnaeus)           |          | 2.0, and 4.0 ml.
 --------------------------+----------+---------------------------------
 _Passer domesticus_       |   1.40   | Series 1: Subcutaneous, 0.5,
                           |          | 1.0, 2.0, and 4.0 ml.
 --------------------------+----------+---------------------------------
 _Estrilda amandava_       |   0.45   | [A]Series 1: Intravenous, 0.5,
                           |          | 1.0, 2.0, and 4.0 ml.
                           |          |
                           |          | [A]Series 2: Subcutaneous, 0.5,
                           |          | 1.0, and 2.0 ml.
                           |          |
                           |          | Intraperitoneal, 8.0 ml.
 --------------------------+----------+---------------------------------
 _Poephila guttata_        |   0.56   | [A]Same as for _Estrilda_.
 --------------------------+----------+---------------------------------
 _Molothrus ater_          |   0.65   | Series 1: Intravenous and
                           |          | subcutaneous, respectively, 0.5
                           |          | and 0.5 ml., 1.0 and 1.0 ml.,
                           |          | 3.0 and 1.0 ml., 5.0 and 3.0 ml.
                           |          |
                           |          | Series 2: Subcutaneous, 0.5,
                           |          | 1.0, 2.0 and 4.0 ml.
 --------------------------+----------+---------------------------------
 _Piranga rubra_           |   0.50   | Same as for _Molothrus_.
 --------------------------+----------+---------------------------------
 _Richmondena cardinalis_  |   0.70   | [A]Same as for _Estrilda_.
 --------------------------+----------+---------------------------------
 _Richmondena cardinalis_  |   0.60   | Same as for _Spinus_.
 --------------------------+----------+---------------------------------
 _Passerina cyanea_        |   0.45   | Antiserum not prepared.
 --------------------------+----------+---------------------------------
 _Spiza americana_         |   0.70   | Same as for _Molothrus_.
 --------------------------+----------+---------------------------------
 _Carpodacus purpureus_    |   0.50   | Antiserum not prepared.
 --------------------------+----------+---------------------------------
 _Spinus tristis_          |   0.49   | Series 1: Intravenous, 0.5, 1.0,
                           |          | 2.0, and 4.0 ml.
                           |          |
                           |          | Series 2: Intravenous, 0.5, 1.0,
                           |          | 2.0, and 4.0 ml.
                           |          |
                           |          | Series 3: Subcutaneous, 0.5,
                           |          | 1.0, 2.0, and 4.0 ml.
 --------------------------+----------+---------------------------------
 _Pipilo erythrophthalmus_ |   0.92   | Antiserum not prepared.
 --------------------------+----------+---------------------------------
 _Junco hyemalis_          |   0.56   | Same as for _Spinus_.
 --------------------------+----------+---------------------------------
 _Spizella arborea_        |   0.48   | Same as for _Spinus_.
 --------------------------+----------+---------------------------------
 _Zonotrichia querula_     |   0.48   | Same as for _Spinus_.
 --------------------------+----------+---------------------------------
 _Zonotrichia albicollis_  |   0.92   | Antiserum not prepared.
         (Gmelin)          |          |
 --------------------------+----------+---------------------------------

    [A] Antiserum prepared against formolized antigen.


Preparation of Antisera

All antisera were produced in rabbits (laboratory stock of
_Oryctolagus cuniculus_). Three methods of injection of antigen were
used in various combinations: intravenous, subcutaneous, and
intraperitoneal. Injection schedules used in the production of each
antiserum are listed in Table 1. Both formolized and "native" antigens
were used. Each rabbit received one or more series of four injections,
each injection being administered on alternate days and doubling in
amount: 0.5 ml., 1.0 ml., 2.0 ml., and 4.0 ml. In all but two
instances more than one series of injections was necessary to produce
a useful antiserum. More than two series, however, resulted in little
or no improvement of the reactivity of the antiserum.

The injection-series were separated by intervals of eight days. On the
eighth day after the last injection of each series, 10 ml. of blood
were withdrawn from the main artery of the ear of the rabbit, and the
antiserum was used in a homologous precipitin test to determine its
usefulness. If the antiserum contained sufficient amounts of
antibodies to conduct the projected tests, the rabbit was completely
exsanguinated by cardiac puncture, by using an 18-gauge needle and a
50 ml. syringe. The whole blood was placed in clean test tubes and
allowed to clot. It was allowed to stand at 2 deg.C. for 12 to 18 hours so
that most of the serum would be expressed from the clot. The serum was
then decanted, centrifuged to remove all blood cells, sterilized in a
Seitz filter, bottled in sterile vials, and stored at 2 deg.C. until used.


Methods of Serological Testing

The precipitin reaction is the most successful of the serological
techniques thus far devised for systematic comparisons. The reaction
occurs because antigenic substances introduced into the body of an
animal cause the formation of antibodies which precipitate antigens
when the two are mixed. The antisera which are produced show
quantitative specificities in their actions; therefore, when an
antiserum containing precipitins is mixed with each of several
antigens, the reaction involving the homologous antigen (that used in
the production of the antiserum) is greater than those reactions
involving the heterologous antigens (antigens other than those used in
the production of the antiserum). Furthermore, the magnitudes of the
reactions between the antiserum and the heterologous antigens vary
according to the degrees of similarity of these antigens to the
homologous one.

The method of precipitin testing follows that outlined by Leone
(1949). The Libby (1938) Photronreflectometer was used to measure the
turbidities developed by the interaction of antigen and antiserum.
With this instrument parallel rays of light are passed through the
turbid systems being measured. Light rays are reflected from the
suspended particles to the sensitive plate of a photoelectric cell;
this generates a current of electricity which causes a deflection on a
galvanometer. The deflection is proportional to the amount of
turbidity developed and readings may be taken directly from the scale
of the instrument.

The reaction-cells of the photronreflectometer are designed to operate
with a volume of 2 ml.; therefore, this volume was used in all
testing. In every series of tests the amount of antiserum was held
constant and the amount of antigen was varied. The volume for each
antigen dilution was always 1.7 ml., and to this was added 0.3 ml. of
antiserum to make up a volume of 2 ml.

  TABLE 2.--Percentage values obtained from analyses of precipitin
  reactions. Numerals represent relative amounts of reaction between
  antigens and antisera. Homologous reactions are arbitrarily valued
  as 100 per cent, and heterologous reactions are expressed
  accordingly. _Comparisons are meaningful only if made within each
  horizontal row of  values._

  Table headings:
    Col A:  _Estrilda amandava_
    Col B:  _Poephila guttata_
    Col C:  _Piranga rubra_
    Col D:  _Richmondena cardinalis_
    Col E:  _Spiza americana_
    Col F:  _Spinus tristis_
    Col G:  _Junco hyemalis_
    Col H:  _Zonotrichia querula_

 ========================+==============================================
                         |                   ANTISERA
        ANTIGENS         +-----+-----+-----+-----+-----+-----+-----+----
                         |  A  |  B  |  C  |  D  |  E  |  F  |  G  |  H
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Passer domesticus_     |  75 |  74 |  73 |  66 |  81 |  72 | ... |  81
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Estrilda amandava_     | 100 |  88 |  75 | ... |  79 |  72 |  53 | ...
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Poephila guttata_      |  95 | 100 |  77 |  67 |  87 |  81 | ... | ...
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Molothrus ater_        |  66 |  54 |  69 |  65 |  86 |  75 |  69 |  75
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Piranga rubra_         | ... | ... | 100 | ... | ... | ... | ... |  89
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Richmondena cardinalis_|  75 |  80 |  91 | 100 |  98 |  65 |  88 |  91
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Spiza americana_       |  65 |  68 | ... |  71 | 100 |  64 |  67 |  80
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Carpodacus purpureus_  |  70 |  71 |  71 |  61 |  89 |  93 |  53 |  70
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Spinus tristis_        |  72 |  74 |  73 |  60 |  89 | 100 |  60 | ...
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Junco hyemalis_        |  64 |  56 |  74 |  65 |  87 | 68  | 100 | ...
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----
 _Zonotrichia querula_   |  65 |  71 | ... |  67 |  89 | 75  | ... | 100
 ------------------------+-----+-----+-----+-----+-----+-----+-----+----

Antigens were diluted with 0.9 per cent phosphate-buffered saline
solution. Tests were run in standard Kolmer test-tube racks, each test
consisting of 12 tubes. Each dilution was made on the basis of the
known protein concentration of the antigen. The first tube contained
an initial dilution of 1 part protein in 250 parts saline and each
successive tube contained a protein dilution one-half the
concentration of the preceding tube, ranging up to 1:512,000. Saline
controls, antiserum controls, and antigen controls were maintained
with each test to determine the turbidities inherent in these
solutions. These control-turbidities were deducted from the total
turbidity developed in each reaction-tube, the resultant turbidity
then being considered as that which was caused by the interaction of
antigens and antibodies. The turbidities were allowed to develop over
a 24-hour period. In the early stages of this investigation the
reactions were allowed to take place at 2 deg.C. in order to inhibit
bacterial growth.

Later tests were carried out at room temperatures, and bacterial
growth was prevented by the addition to each tube of 'Merthiolate' in
a final dilution of 1:10,000.


Experimental Data

Corrected values for the turbidities obtained were plotted with the
turbidity values on the ordinate and the antigen dilutions on the
abscissa. The homologous reaction was the standard of reference for
all other test reactions with the same antiserum. By summing the
plotted turbidity readings, numerical values are obtained which are
indices serving to characterize the curves. Such values were converted
to percentage values, that of the homologous reaction being considered
100 per cent. These values, plus the curves, provide the data by means
of which the proteins of the birds may be compared. Plots
representative of the precipitin curves are presented in Figs. 10 to
21. For convenience each plot represents only several of the 10 curves
obtained with each antiserum.

A summary of the serological relationships of the birds involved in
the precipitin tests is presented in Table 2, in which percentage
values are presented. Since the techniques involved in testing were
greatly improved as the investigation proceeded, the summary is based
solely on those tests run in the later stages of the investigation.
For reasons which will become apparent in later discussion, it should
be emphasized that in Table 2 comparisons may be made only within each
horizontal row of values.


Discussion of the Serological Investigations

One of the problems met early in this investigation was instability of
the proteins in the extracts that were prepared. Extracts in which no
attempt was made to inactivate the enzymes present proved
unsatisfactory. It was necessary to maintain the temperature of the
"native" antigens at 2 deg.C, and all work with such antigens had to be
performed at this temperature. This arrangement was inconvenient;
furthermore, inactivation of the enzymes was not complete even at this
low temperature, and some denaturation of the proteins took place as
evidenced by the gradual appearance of insoluble precipitates in the
stored vials.

The preservatives, 'Merthiolate' and formalin, were used in an attempt
to inhibit the autolytic action of the enzymes present. Formalin, when
added to make a final dilution of 0.4 per cent, proved to be the more
satisfactory of the two preservatives and was used throughout most of
the work. Formalin caused slight denaturation of some of the proteins,
but this effect was complete within a few hours, after which any
denatured material was removed by filtration or centrifugation. The
proteins remaining in solution were stable over the period necessary
to complete the investigations.

The addition of formalin reduces the reactivity of the extracts when
they are tested with antisera prepared against "native" antigens and
causes changes in the nature of the precipitin curves. This effect has
been pointed out by Horsfall (1934) and by Leone (1953) in their work
on the effects of formaldehyde on serum proteins. Their data indicate,
however, that even though changes in the immunological characteristics
of proteins are brought about by formolization, the proteins retain
enough of their specific chemical characteristics to allow consistent
differentiation of species by immunological methods. In the tests
which I performed, the relative positions of the precipitin curves,
whether native or formolized extracts were involved, remained
unchanged (Figs. 10, 11). _All data used in interpretation of the
serological relationships were obtained from tests in which formolized
antigens of equivalent age were used._

Only three antisera were produced against formolized antigens, all
others being produced against "native" extracts. The formolized
antigens seemed to have a greater antigenicity, in most instances,
than did those which were unformolized, and precipitin reactions
involving antisera produced against formolized antigens developed
higher turbidities. The antisera produced against formolized antigens
were equal to but no better than those prepared against "native"
extracts in separating the birds tested (Figs. 12, 13).

The rabbit is a variable to be considered in serological tests. Two
rabbits exposed to the same antigen, under the same conditions, may
produce antisera which differ greatly in their capacities to
distinguish different antigens. It is logical to assume, therefore,
that two rabbits exposed to different antigens may produce antisera
which also differ in this respect. This explains the unequal values of
reciprocal tests shown in Table 2. Thus, in the test involving the
antiserum to the extracts of _Richmondena_, a value of 71 per cent was
obtained for _Spiza_ antigen, whereas in the test involving
anti-_Spiza_ serum, a value of 98 per cent was obtained for
_Richmondena_ antigen. In Table 2, therefore, comparisons may be made
only among values for the proteins of birds tested with the same
antiserum.

Since the amount of any one antiserum is limited, there is, of
necessity, a limit as to the number of birds used in a series of
serological tests. Therefore, although the results reveal the actual
serological relationships of the individual species, interpretation of
the relationships of the taxonomic groups must be undertaken with the
realization that such an interpretation is based on tests involving
relatively few species of each group. It is reasonable to assume,
however, that a species which has been placed in a group on the basis
of resemblances other than serological resemblance would show greater
serological correspondence to other members of that group than it
would to members of other groups. Specifically, in the Fringillidae
and their allies, there seems to be little reason to doubt that
genera, and even subfamilies, are natural groups. This is illustrated
in tests involving closely related genera: _Richmondena_ and _Spiza_
(Figs. 14, 15, 18), _Estrilda_ and _Poephila_ (Fig. 21), _Spinus_ and
_Carpodacus_ (Figs. 12, 17, 19, 20). In each of these tests the pairs
of genera mentioned show greater serological correspondence to each
other than they do to other kinds involved. This point is illustrated
further by a test (not illustrated) involving _Zonotrichia querula_
(the homologous antigen) and _Zonotrichia albicollis_. Although this
test was one of an earlier series in which difficulties were
encountered (the data, therefore, were not used), it is of interest
that the two species were almost indistinguishable serologically.

The serological homogeneity of passeriform birds is emphasized by the
fact that the value of every heterologous reaction was more than 50
per cent of the value of the homologous reaction, except in the test
involving the anti-_Richmondena_ serum and _Myiarchus_ (Fig. 13) in
which the value of the heterologous reaction was 45 per cent. Because
most ornithologists consider these genera to be only distantly related
(they are in different suborders within the Order Passeriformes), the
relatively high value of the heterologous reaction emphasizes the
close serological correspondence of passerine birds and indicates that
small consistent serological differences among these birds are
actually significant. The possibility that some of the serological
correspondence is due to the "homologizing" effect of formalin on
proteins should not be excluded. I think, however, that this effect is
not entirely responsible for the close correspondence observed here.

An additional point to consider in interpretation of the serological
tests is that the techniques used tend to separate sharply species
that are closely related whereas species that are distantly related
are not so easily separated. In other words, comparative serological
studies with the photronreflectometer tend to minimize the differences
between distant relatives and to exaggerate the differences between
close relatives.

In analyzing the serological relationships of the species used in this
study, it becomes obvious that two or more series of tests must be
considered before the birds can be placed in relation to each other.
For example, the data presented in Fig. 14 indicate that _Spiza_ and
_Molothrus_ show approximately the same degree of serological
correspondence to _Richmondena_. This does not imply necessarily that
_Spiza_ and _Molothrus_ are closely related. If Fig. 15 is examined,
it can be determined that _Richmondena_ shows much greater serological
correspondence to _Spiza_ than does _Molothrus_. Thus, an analysis of
both figures serves to clarify the true serological relationships of
the three genera. By reference to other series of tests involving
these three birds a more exact determination of their relationships
may be obtained.

To illustrate this point by a hypothetical example, two species might
seem equidistant, serologically, from a third species. Additional
testing should indicate if the first two species are equidistant in
the same direction (therefore, by implication, close relatives) or in
opposite directions (therefore, distant relatives). A single test
supplies only two dimensions of a three dimensional arrangement.

It is impossible to interpret and to picture the serological data
satisfactorily in two dimensions; therefore, a three-dimensional model
(Figs. 22, 23) was constructed to summarize the serological
relationships of the birds involved. Each of the eleven kinds used
consistently throughout the investigation is represented in the model.
By use of the percentage values (Table 2), each bird was located in
relation to the other birds. Where possible, averages of reciprocal
tests (Table 3) were used in determining distances between the
elements of the model. In this way seven of the birds were accurately
located in relation to each other. Lacking reciprocal tests, the
positions of the other birds were determined by the values of single
tests (Table 4). Although these birds were placed with less certainty,
at least four points of reference were used in locating each species.
At least one serological test is represented by each connecting bar in
the model. The lengths of the bars connecting any two elements were
determined as follows: a percentage value (Table 3 and Table 4)
representing the degree of serological correspondence between two
birds was subtracted from 100 per cent; the remainder was multiplied
by a factor of five to increase the size of the model and the product
was expressed in millimeters; a bar of proper length connects the two
elements involved.

From the model it is observed that, _Molothrus_ and _Passer_ excluded,
the birds fall into two distinct groups: one includes _Piranga_,
_Richmondena_, _Spiza_, _Junco_, and _Zonotrichia_; the other includes
_Estrilda_, _Poephila_, _Carpodacus_, and _Spinus_.

  TABLE 3.--Reciprocal Values Used to Determine Distances Between
    Elements of the Model; Each Value Represents the Average of
          Serological Tests Between the Species Involved

  Table Headings:
    Col A: _Estrilda amandava_
    Col B: _Poephila guttata_
    Col C: _Richmondena cardinalis_
    Col D: _Spiza americana_
    Col E: _Spinus tristis_
    Col F: _Junco hyemalis_
    Col G: _Zonotrichia querula_

 ==========================+====+====+====+====+====+====+====+
                           |  A |  B |  C |  D |  E |  F |  G |
 --------------------------+----+----+----+----+----+----+----+
 _Estrilda amandava_       | .. | 92 | .. | 72 | 72 | 59 | .. |
 --------------------------+----+----+----+----+----+----+----+
 _Poephila guttata_        | 92 | .. | 74 | 78 | 78 | .. | .. |
 --------------------------+----+----+----+----+----+----+----+
 _Richmondena cardinalis_  | .. | 74 | .. | 85 | 63 | 77 | 79 |
 --------------------------+----+----+----+----+----+----+----+
 _Spiza americana_         | 72 | 78 | 85 | .. | 77 | 77 | 85 |
 --------------------------+----+----+----+----+----+----+----+
 _Spinus tristis_          | 72 | 78 | 63 | 77 | .. | .. | .. |
 --------------------------+----+----+----+----+----+----+----+
 _Junco hyemalis_          | .. | .. | 77 | 77 | .. | .. | .. |
 --------------------------+----+----+----+----+----+----+----+
 _Zonotrichia querula_     | .. | .. | 79 | 85 | .. | .. | .. |
 --------------------------+----+----+----+----+----+----+----+

  TABLE 4.--Single Values Used to Determine Distances Between Elements
      of the Model; Each Value Represents a Single Test Between the
                           Species Involved

  Table headings:
    Col A: _Estrilda amandava_
    Col B: _Poephila guttata_
    Col C: _Piranga rubra_
    Col D: _Richmondena cardinalis_
    Col E: _Spinus tristis_
    Col F: _Junco hyemalis_
    Col G: _Zonotrichia querula_

 ==========================+====+====+====+====+====+====+====+
                           |  A |  B |  C |  D |  E |  F |  G |
 --------------------------+----+----+----+----+----+----+----+
 _Passer domesticus_       | .. | 74 | 73 | .. | 72 | .. | .. |
 --------------------------+----+----+----+----+----+----+----+
 _Molothrus ater_          | .. | 54 | .. | 65 | .. | 69 | 75 |
 --------------------------+----+----+----+----+----+----+----+
 _Piranga rubra_           | .. | 77 | .. | 91 | 73 | 74 | .. |
 --------------------------+----+----+----+----+----+----+----+
 _Carpodacus purpureus_    | 70 | 71 | .. | 61 | 93 | .. | .. |
 --------------------------+----+----+----+----+----+----+----+

  [Illustration: FIGS. 10-13. Graphs of precipitin reactions
      illustrating effects of formalin on antigenicity and reactivity
      of the extracts. For further information, see text, pp. 190-193.

  FIG. 10. Reactions of unformolized antigens of _Richmondena_,
    _Zonotrichia_, and _Molothrus_ with anti-_Richmondena_ serum.
  FIG. 11. Reactions of formolized antigens of _Richmondena_,
    _Zonotrichia_, and _Molothrus_ with anti-_Richmondena_ serum.
  FIG. 12. Reactions of anti-_Richmondena_ serum prepared against
    native antigen with antigens of _Richmondena_, _Zonotrichia_,
    _Carpodacus_, and _Spinus_.
  FIG. 13. Reactions of anti-_Richmondena_ serum prepared against
    formolized antigen with antigens of _Richmondena_, _Zonotrichia_,
    _Poephila_, _Spinus_, and _Myiarchus_.]

  [Illustration: FIGS. 14-17. Graphs of precipitin reactions
      illustrating serological relationships. For further explanation,
      see text, pp. 190-193.

  FIG. 14. Serological relationships of _Richmondena_, _Spiza_, and
    _Molothrus_.
  FIG. 15. Serological relationships of _Richmondena_, _Spiza_, and
    _Molothrus_.
  FIG. 16. Serological relationships of _Carpodacus_ with the
    richmondenine-emberizine-thraupid assemblage.
  FIG. 17. Serological relationships of _Carpodacus_ and _Spinus_ with
    _Richmondena_ and _Junco_.]

  [Illustration: FIGS. 18-21. Graphs of precipitin reactions
      illustrating serological relationships. For further explanation,
      see text, pp. 190-193.

  FIG. 18. Serological relationships of _Spinus_ and _Poephila_ with
    the richmondenines.
  FIG. 19. Serological relationships of _Carpodacus_ and _Spinus_
    with _Richmondena_ and _Piranga_.
  FIG. 20. Serological relationships of _Poephila_ and Richmondena
    with the carduelines.
  FIG. 21. Serological relationships of _Richmondena_ and _Spinus_
    with the estrildines.]

  [Illustration: FIG. 22. Two views of a model illustrating
      serological relationships among fringillid and related birds.
      For further explanation, see text, pp. 193-194.

             Genera               Pi  . . . .  _Piranga_
        C  . . . .  _Carpodacus_  Po  . . . .  _Poephila_
        E  . . . .  _Estrilda_    R   . . . .  _Richmondena_
        J  . . . .  _Junco_       Sn  . . . .  _Spinus_
        M  . . . .  _Molothrus_   Sz  . . . .  _Spiza_
        Pa . . . .  _Passer_      Z   . . . .  _Zonotrichia_]

  [Illustration: FIG. 23. Two additional views of the model shown in
      fig. 22 illustrating serological relationships among fringillid
      and related birds. For further explanation, see text,
      pp. 193-194.

             Genera               Pi  . . . .  _Piranga_
        C  . . . .  _Carpodacus_  Po  . . . .  _Poephila_
        E  . . . .  _Estrilda_    R   . . . .  _Richmondena_
        J  . . . .  _Junco_       Sn  . . . .  _Spinus_
        M  . . . .  _Molothrus_   Sz  . . . .  _Spiza_
        Pa . . . .  _Passer_      Z   . . . .  _Zonotrichia_]

Within the richmondenine-emberizine-thraupid assemblage, _Junco_
and _Zonotrichia_ constitute a sub-group apart from the others.
_Piranga_ and _Richmondena_ show close serological correspondence.
The present taxonomic position of _Spiza_ in the Richmondeninae,
which has been questioned by Beecher (1951a:431; 1953:309), is
corroborated at least insofar as the serological evidence is
concerned. Certainly, serological correspondence of _Spiza_ with the
richmondenine-emberizine-thraupid assemblage is greater than with any
other group of birds tested.

It is obvious that the serological affinities of the carduelines do
not lie with the richmondenines, emberizines, or thraupids. The
carduelines show greater serological correspondence with the
estrildines than they do with any of the other groups tested. Further
serological investigation involving other species, however, is
necessary before the nearest relatives of the carduelines can be
determined with certainty.

The two estrildines tested (_Estrilda_ and _Poephila_) show close
serological relationship. Their nearest relatives, serologically, seem
to be the carduelines. The classification (Wetmore, 1951) that places
_Passer_ in the same family with the estrildines is not upheld by the
serological data available. _Passer_ is not, serologically, closely
related to any of the birds tested. It is of interest that Beecher
(1953:303-305), on the basis of jaw musculature, places _Passer_ and
the estrildines in separate families (Ploceidae and Estrildidae,
respectively).

_Molothrus_ shows greater serological correspondence to the
richmondenine-emberizine-thraupid assemblage than to any of the other
birds tested. It is definitely set apart from this group, however, and
its position, serologically, is compatible with that based on evidence
from other sources.

There seems to be but little argument among ornithologists that
icterids, fringillids, and ploceids constitute families which are
distinct from one another. If, then, the serological differences
between _Molothrus_ (Icteridae) and _Richmondena_ (Fringillidae),
between _Molothrus_ and _Zonotrichia_ (Fringillidae), and between
_Richmondena_ and _Poephila_ (Ploceidae) are indicative of family
differences, there are four families represented by the birds
involved. _Molothrus_ represents one family; _Piranga_, _Richmondena_,
_Spiza_, _Junco_, and _Zonotrichia_, a second; _Estrilda_, _Poephila_,
_Carpodacus_, and _Spinus_, a third; and _Passer_, a fourth.




CONCLUSIONS


The heterogeneity of the Family Fringillidae has been emphasized by
many authors. The relationships of the species now included in this
Family have been the subject of much discussion and constitute an
important problem in avian systematics.

Sushkin's studies (1924, 1925) of features of the horny and bony
palates have served as a basis for the present division of the Family
into subfamilies. Recently, Beecher (1951a, 1951b, 1953) and Tordoff
(1954) have used these features and others which they thought to be of
value in an attempt to clarify the relationships of the species
involved.

Beecher's work (1951a, 1951b, 1953) on jaw-musculature is a valuable
contribution to our knowledge of the anatomy of passerine birds. His
myological studies were so thorough and his presentation so detailed
that students who disagree with his interpretations can draw their own
conclusions. Beecher (1951b:276) points out that there are two basic
types of skeletal muscle--those with parallel fibers and those with
pinnately arranged fibers. The muscles with pinnate fibers seem to be
more efficient, each muscle having a greater functional cross section
for its bulk than does one with parallel fibers. He assumes that
muscles with parallel fibers are more primitive, phylogenetically,
than are those with fibers arranged pinnately. Since his study of the
jaw muscles of the Icteridae (1951a) revealed that patterns of
jaw-musculature within this Family remain constant regardless of the
methods used in procuring food, he assumes that such patterns may be
used as indicators of relationship throughout the entire oscinine
group. These two assumptions, then, serve as the basis for his
hypothesis concerning relationship and phylogeny within this
assemblage. Beecher (1951b:278-280; 1953:310-312) maintains that
within the Family Thraupidae there are two main lines which lead with
almost no disjunction to the Carduelinae and Richmondeninae. The
thraupid-richmondenine line involves a shift in the nature of the _m.
adductor mandibulae externus superficialis_, which becomes more
pinnate in the richmondenines. This results in greater crushing power.
The thraupid-cardueline line involves a shift in emphasis from the the
_m. adductor mandibulae externus medialis_ to the _m. pseudotemporalis
superficialis_ and the forward advance of the insertion of the latter.
This, also, promotes greater crushing ability. He states that features
of the horny palate and of the plumage provide further evidence of
close relationship of these groups. He includes, therefore, the
Thraupinae, the Carduelinae, and the Pyrrhuloxiinae (=Richmondeninae)
in the Family Thraupidae. Beecher (1953:307) indicates that the
patterns of jaw-musculature of the Parulinae (wood warblers) and
Emberizinae (buntings) are similar and suggests that the buntings had
their origin from the wood warblers. He includes these subfamilies,
therefore, in the Family Parulidae.

Beecher's reasoning may be criticized on several points. It may be, as
he suggests, that muscles with parallel fibers evolved earlier,
phylogenetically, than did muscles with pinnate fibers, but he does
not give adequate consideration, it seems to me, to the possibility
that parallel fibers may also have evolved secondarily from pinnate
fibers. Since Beecher (1951a) found that patterns of jaw-musculature
within the Family Icteridae were conservative, he is reluctant to
admit the possibility of convergence among any of the other families.
Differences in patterns of jaw-musculature are, however, functional
adaptations and like the bill, which is also associated with
food-getting may be subject to rapid evolutionary change. Finally, in
attempting to classify the oscines, he has relied almost entirely on a
single character--the pattern of jaw-musculature.

Tordoff's attempts (1954) to clarify the relationships of the
fringillids and related species are based chiefly on features of the
bony palate. He assumes that since palato-maxillaries seem to be
absent in the majority of passerine birds, their occurrence in certain
nine-primaried oscine groups indicates relationship among these
groups. He points out that these bones, when present, are important
areas of origin of the _m. pterygoideus_ which functions in depression
of the upper jaw and in elevation of the lower jaw. He assumes,
therefore, that palato-maxillaries were evolved to provide for a more
effective action of the _m. pterygoideus_. The need for such action
could be associated with a seed-eating habit. All richmondenines and
emberizines possess palato-maxillary bones either free or fused to the
prepalatine bar, but there is no trace of these bones in the
carduelines. Carduelines, furthermore, possess prepalatine bars that
are characteristically flared anteriorly. This condition does not
exist in the richmondenines or in the emberizines.

Tordoff points out, also, that the irregular, erratic migrations of
the New World Carduelinae are unlike the more regular migrations of
the richmondenines and emberizines. The carduelines, furthermore, are
more arboreal in their habits than are these other groups and exhibit
a decided lack of nest sanitation during the later stages of nesting,
a situation which contrasts with that found in the Richmondeninae and
Emberizinae. He suggests, therefore, that the carduelines are not so
closely related to the richmondenines and the emberizines as
previously has been thought.

Since there are only two cardueline genera, _Loximitris_ and
_Hesperiphona_, endemic to the New World and at least 10 genera with
many species endemic to the Old World, Tordoff (1954:15) suggests an
Old World origin for the carduelines. He strengthens his argument for
this hypothesis by pointing out that in features of the bony palate
and in habits the carduelines resemble the estrildines of the Family
Ploceidae.

Tordoff (1954:29-30) states that the tanagers not only merge with the
richmondenines but also grade imperceptibly into the emberizines. He
includes, therefore, the Richmondeninae, Emberizinae, and Thraupinae
in the Family Fringillidae. He suggests that the carduelines are
ploceids, closely related to the Subfamily Estrildinae, on the basis
of structure of the bony palate, geographic distribution, social
behavior, and habits such as nest-fouling and nest-building.

Tordoff, like Beecher, has based his interpretations chiefly on one
feature--structure of the bony palate. Since this feature also is
associated with food-getting, the possibilities of convergence of
distantly related species with similar habits and divergence of
closely related species with different habits may not be excluded.

The hazard of unrecognized adaptive convergence cannot, of course, be
excluded from most fields of taxonomic research, but some features of
morphology and biochemistry are notably more conservative than others
and undergo slower evolutionary change. Such features are often of
utmost importance in distinguishing the higher taxonomic categories.

Most ornithologists are aware that, within the Order Passeriformes,
patterns of musculature in the leg have evolved at a slow rate and
exhibit little variation within the Order. Differences which do occur,
therefore, probably are significant, especially those that are
consistent between groups of species. As I have pointed out earlier
(p. 184), there are no significant differences in leg-musculature
between the Richmondeninae, Emberizinae, and Thraupidae. Indeed, it is
difficult to define these groups on the basis of leg-musculature. If
these groups are of common origin, the lack of distinct boundaries
between them is not surprising. A muscular band which extends from the
_pars interna_ of the _m. gastrocnemius_ around the front of the knee
is present in every emberizine species that I studied and in the Genus
_Piranga_. With the exception of _Spiza_ none of the richmondenines
possesses this band.

The significant differences in leg-musculature which have been
discussed above (pp. 183-184) distinguish the carduelines from the New
World finches and tanagers. Even the cardueline _Leucosticte_ and the
emberizine _Calcarius_, which resemble one another in general
adaptations and in several myological features of the leg (p. 183),
agree in significant features of the musculature with the respective
groups to which they belong. The carduelines agree in the major
features of leg-musculature with the ploceids which I studied.

The use of serological techniques in taxonomic work has two main
advantages. The biochemical systems involved in such investigations
seem to be relatively slow to change in response to external
environmental influences, and the quantitative nature of the results
obtained makes possible objective measurement of resemblances among
species.

I have pointed out (p. 200) that the carduelines are excluded,
serologically, from the distinct assemblage formed by the
richmondenines, emberizines, and tanagers. Actually, the carduelines
show less serological resemblance to this assemblage than do the
estrildines, and most ornithologists agree that the Estrildinae are
not at all closely related to the Richmondeninae, Emberizinae, and
Thraupidae. _Molothrus_, representing a family (Icteridae) recognized
as distinct from the Family Fringillidae, also more closely resembles
the fringillid assemblage, serologically, than do the carduelines.
Although the Carduelinae constitute a distinct group serologically,
they show greater serological resemblance to the estrildines of the
Family Ploceidae than to any of the other species tested. At least the
carduelines and the estrildines form a group as compact as the
subfamilies of the Fringillidae. Thus, the serological data correlate
well with those obtained from the study of the leg-musculature.

Present systems of classification include the subfamilies Passerinae
and Estrildinae in the Family Ploceidae. _Passer_, however, is less
closely related to the estrildines serologically than are the
carduelines, and is less closely related to the estrildines than
_Molothrus_, an icterid, is to the fringillids. This raises a question
as to the homogeneity of the Family Ploceidae as presently recognized
by most ornithologists. If the Passerinae and the Estrildinae are
placed in a single family, the serological divergence among members of
this group is certainly greater than it is in the Family Fringillidae.
Additionally, Beecher (1953:303-304) found that the estrildines
possess a pattern of jaw-musculature different from those in other
ploceids.

The combined evidence from jaw-musculature and serology has caused me
to conclude that the estrildines should be excluded from the Family
Ploceidae (see below).

In an attempt to clarify the relationships of the Fringillidae and
allied groups, I here review briefly the evidence which has been
presented. From his studies of jaw-musculature (1951a, 1951b,
1953) Beecher concludes that the Pyrrhuloxinae (=Richmondeninae),
the Carduelinae, and the Thraupinae are closely related.
He places these groups in the Family Thraupidae. He excludes the
Emberizinae from this group and places them with the wood warblers
in the Family Parulidae. He suggests that the estrildines constitute
a family (Estrildidae) separate from the Family Ploceidae.

From his studies of certain features of the bony palate Tordoff
(1954:25-26, 32) concludes that the richmondenines, the emberizines,
and the tanagers have a common origin and places these groups in the
Family Fringillidae. He excludes the carduelines from this assemblage,
suggests that they are closely related to the estrildines, and
includes them as the Subfamily Carduelinae in the Family Ploceidae.

In this paper I have presented data obtained from the study of certain
features of morphology and biochemistry which I think are less subject
to the influence of environmental factors than those features studied
by recent workers. It is significant that the data obtained by use of
serological techniques and those obtained from the study of
leg-musculature point to the same conclusions. On the basis of these
data I have drawn several conclusions concerning the relationships of
the groups which I studied.

The richmondenines, emberizines, and tanagers are closely related and
should be included in a single family, Fringillidae. The Carduelinae
and the Estrildinae are closely related subfamilies. Although most
recent classifications place the Estrildinae and Passerinae in the
Family Ploceidae, the serological evidence indicates that these groups
are not closely related. Beecher (1953:303-304) drew the same
conclusion from his study of jaw-musculature (see above). I suggest,
therefore, that the Carduelinae and the Estrildinae be placed in a
family separate from the Ploceidae and that the name Carduelidae
(rather than Estrildidae) be used for this group. At present, neither
is an accepted family name. Because _Carduelis_ Brisson 1760 is an
older name than _Estrilda_ Swainson 1827 and because _Carduelis_ seems
to be a centrally located genus in the family, I have chosen the
former (although the International Rules of Zoological Nomenclature do
not specify that priority must apply in forming family names).

I have been unable to study any of the species included in the
subfamilies Fringillinae (not Fringillinae of Tordoff, see 1954:23-24,
and below) and Geospizinae of recent classifications; thus these
groups have not been discussed above. Beecher (1953:307-308) includes
_Fringilla_ in the Subfamily Carduelinae; he includes the geospizines
in a separate family, Geospizidae, and states that they are derived
from the emberizines. Tordoff (1954:23-24) found that in features of
the bony palate _Fringilla_ and the geospizines resemble the
emberizines and, on this basis, includes them in the Subfamily
Fringillinae.

The Dickcissel, _Spiza americana_, possesses certain features which
merit special discussion. Beecher (1951a:431; 1953:309), on the basis
of jaw-musculature, considers it an icterid. To be sure _Spiza_ is in
many ways an aberrant member of the group to which it is now assigned
(Subfamily Richmondeninae). _Spiza_, serologically, is closely related
to all species of the richmondenine-emberizine-thraupid assemblage.
Within this assemblage its nearest relatives are the richmondenines.
_Spiza_ differs from the other richmondenines studied and resembles
the emberizines and tanagers in the possession of the muscular band
which extends from the _pars interna_ of the _m. gastrocnemius_ around
the front of the knee. This band, in _Spiza_, is smaller, however,
than in any of the other species. No icterid dissected possesses such
a structure. Tordoff (1954:29) states that _Spiza_ is typically
richmondenine in palatal structure and makes the suggestion, with
which I agree, that _Spiza_ is a richmondenine and may be closely
related to the ancestral stock which gave rise to the fringillid
assemblage. The serological position of _Spiza_, approximately
equidistant from the other fringillids (Figs. 22, 23), and the
presence of the small muscular band around the front of the knee
constitute evidence supporting the central position of _Spiza_.

After consideration of evidence from the studies of external
morphology, ethology, myology, osteology, and serology, I propose here
an arrangement of the groups which I have studied and submit for
comparison the arrangements (of these groups) proposed by Beecher and
Tordoff. The names of subfamilies that I have been unable to study are
included in my classification and are placed in brackets.

 ------------------------+----------------------+-----------------------
                         | Proposed by Tordoff  |  Proposed by Beecher
      Here proposed:     | (1954) on the basis  |  (1953) on the basis
                         | of the bony palate:  |  of jaw-musculature:
 ========================+======================+=======================
     FAMILY PLOCEIDAE    |   FAMILY PLOCEIDAE   |    FAMILY PLOCEIDAE
                         |                      |
 [Subf. Bubalornithinae] |Subf. Bubalornithinae |
                         |                      |
 Subfamily Passerinae:   |Subfamily Passerinae  | Subfamily Passerinae
 distinguished from the  |                      |
 Estrildinae by patterns |                      |
 of jaw-musculature      |                      |
 (Beecher, 1953:303-304) |                      |
 and on the basis of     |                      |
 comparative serology of |                      |
 saline-soluble proteins.|                      |
                         |                      |
 [Subfamily Ploceinae]   |Subfamily Ploceinae   | Subfamily Ploceinae
                         |                      |
 [Subfamily Viduinae]    |Subfamily Viduinae    | Subfamily Viduinae
                         |                      |
    FAMILY CARDUELIDAE   |                      |
                         |                      |
 Subfamily Estrildinae:  |Subfamily Estrildinae |   FAMILY ESTRILDIDAE
 similar to the          |                      |
 Carduelinae in features |                      |
 of the bony palate and  |                      |
 habits (Tordoff, 1954:  |                      |
 18-22) and in patterns  |                      |
 of leg-musculature and  |                      |
 comparative serology    |                      |
 of saline-soluble       |                      |
 proteins.               |                      |
                         |                      |
 Subfamily Carduelinae:  |Subfamily Carduelinae | [In Thraupidae below]
 distinguished from the  |                      |
 Fringillidae by features|                      |
 of the palate,          |                      |
 geographic distribution,|                      |
 migration patterns, and |                      |
 habits (Tordoff, 1954:  |                      |
 14-18) and by patterns  |                      |
 of leg-musculature and  |                      |
 comparative serology    |                      |
 of saline-soluble       |                      |
 proteins.               |                      |
                         |                      |
 FAMILY FRINGILLIDAE: all| FAMILY FRINGILLIDAE  |   FAMILY PARULIDAE
 members of this family  |                      |  Subfamily Parulinae
 show similarities in    |                      | Subfamily Emberizinae
 features of the bony    |                      |
 palate (Tordoff, 1954:  |                      |
 22-23), patterns of     |                      |
 leg-musculature, and    |                      |
 in comparative serology |                      |
 of saline-soluble       |                      |
 proteins.               |                      |   FAMILY THRAUPIDAE
                         |                      |
 Subf. Richmondeninae    |Subf. Richmondeninae  | Subfamily
                         |                      | Pyrrhuloxiinae
                         |                      |
 Subfamily Thraupinae    |Subfamily Thraupinae  | Subfamily Thraupinae
                         |                      |
 Subfamily Emberizinae   |Subfamily Fringillinae| [In Parulidae above]
                         |(including Emberizinae|
 [Subfamily Fringillinae]|   and Geospizinae)   | Subfamily Carduelinae
                         |                      |
 [Subfamily Geospizinae] |                      |
 ------------------------+----------------------+-----------------------




SUMMARY


It has long been recognized that the Family Fringillidae includes some
dissimilar groups. Specifically, the relationships of the subfamilies
Richmondeninae, Emberizinae, and Carduelinae of the Family
Fringillidae are poorly understood. Data from two recent studies, one
on patterns of jaw-musculature and the other on features of the bony
palate, emphasize the dissimilarity of these subfamilies but have
given rise to conflicting concepts of the relationships of subfamilies
within the Family.

This paper reports the results of studies involving morphological and
biochemical features that I consider less sensitive to external
environmental factors than are features which have been studied
previously. Patterns of leg-musculature were chosen for study because
earlier work showed that muscle patterns in the legs of passerine
birds are highly stable and vary but little. Variations, therefore,
which are consistent in separating groups of species should be
significant. Serological techniques were used because the biochemical
systems involved seem to be relatively slow to change in response to
environmental influences and because the data obtained may be used in
a highly objective manner to measure resemblance among species.

Individual differences in the patterns of leg-musculature were found
to be slight and involved mainly the sizes and shapes of muscles. For
this reason variations involving origin, insertion, or relative
position of a muscle, were judged significant. In leg-musculature the
Richmondeninae, the Emberizinae, and the Thraupidae resemble one
another closely. Several differences in muscle pattern were found,
however, which distinguish these groups from the Carduelinae. The
leg-musculature of the carduelines closely resembles that of the
Ploceidae.

Serological techniques involved the extraction of saline-soluble
proteins from the tissues of the species to be studied. These extracts
were carefully processed and were used as antigens. Formolization of
the antigens was necessary as a means of preventing denaturation of
the proteins by enzymatic activity. Antisera were produced in rabbits.
The method of testing involved turbidimetric analysis of the
precipitin reaction. Utilizing the values for the precipitin tests a
model was constructed which showed the relationships of the eleven
species used in these tests. From a study of the model and the data
used in its construction, it was determined that the Richmondeninae,
Emberizinae, and Thraupidae constitute an assemblage distinct from the
other species studied. The Carduelinae are excluded from the
assemblage and serologically are most closely related to the
Estrildinae. The estrildines, serologically, do not closely resemble
_Passer_, Subfamily Passerinae, although recent classifications place
these two subfamilies in the Family Ploceidae.

Upon consideration of all evidence now available--from external
morphology, ethology, myology, osteology, and serology--several
hypotheses regarding the relationships of the groups studied are set
forth. The richmondenines, emberizines, and tanagers are closely
related subfamilies and are here included in the Family Fringillidae.
The Estrildinae and Carduelinae are closely related subfamilies, but
neither group is closely related to the Passerinae. The estrildines
and carduelines, therefore, are placed in a separate family, the
Carduelidae. In some ways, _Spiza_ is an aberrant member of the
Subfamily Richmondeninae but should be retained in that subfamily. It
is suggested that _Spiza_ is a primitive richmondenine closely related
to the ancestral fringillid stock.




LITERATURE CITED


AMERICAN ORNITHOLOGISTS' UNION

   1931.  Check-list of North American birds. Fourth edition.
          Lancaster, Pa., xix + 526 pp.


BEECHER, W. J.

   1951a. Adaptations for food-getting in the American blackbirds.
          Auk, 68:411-440, 11 figs.

   1951b. Convergence in the Coerebidae. Wilson Bull., 63:274-287,
          5 figs.

   1953.  A phylogeny of the oscines. Auk, 70:270-333, 18 figs.


BERGER, A. J.

   1952.  The comparative functional morphology of the pelvic
          appendage in three genera of Cuculidae.
          Amer. Mid. Nat., 47:513-605, 29 pls.


BOYDEN, A.

   1942.  Systematic serology: a critical appreciation.
          Physiol. Zool., 15:109-145, 12 figs.


CHAPIN, J. P.

   1917.  The classification of the weaver-birds. Bull. Amer. Mus.
          Nat. Hist., 37:243-280, 10 pls., 9 figs.


CUMLEY, R. W., and IRWIN, M. R.

   1941.  Pictorial representation of the antigenic differences
          between two dove species. Jour. Hered., 32:178-182,
          frontispiece, 2 figs.

   1941.  Interaction of antigens in dove hybrids. Ibid., 429-434,
          3 figs.

   1944.  The correlation between antigenic composition and geographic
          range in the Old and New World of some species of _Columba_.
          Amer. Nat., 78:238-256, 1 fig.


DEFALCO, R. J.

   1942.  A serological study of some avian relationships.
          Biol. Bull., 83:205-218.


FISHER, H. I.

   1946.  Adaptations and comparative anatomy of the locomotor
          apparatus of New World vultures. Amer. Mid. Nat.,
          35:545-727, 13 pls., 28 figs.


GADOW, H., and SELENKA, E.

   1891.  Voegel, vol. I, Anatomischer Theil. In Bronn's Klassen und
          Ordnungen des Thier-Reichs, Sechster Band, Vierte Abtheilung.
          Leipzig, 1008 pp., 59 pls.


GARROD, A. H.

   1873.  On certain muscles in the thigh of birds and their value in
          classification. Proc. Zool. Soc. London, Part I:626-644,
          6 figs.

   1874.  On certain muscles in the thigh of birds and their value in
          classification. Ibid., Part II:111-123.


GREENBERG, D. M.

   1929.  The colorimetric determination of serum proteins.
          J. Biol. Chem., 82:545-550.


HELLMAYR, C. E.

   1935.  Catalogue of birds of the Americas. Field Mus. Nat. Hist.,
          Zool. ser. 13, pt. 8, vi + 541 pp.

   1936.  Catalogue of birds of the Americas. Ibid., 13, pt. 9,
          v + 458 pp.

   1937.  Catalogue of birds of the Americas. Ibid., 13, pt. 10,
          v + 228 pp.

   1938.  Catalogue of birds of the Americas. Ibid., 13, pt. 11,
          vi + 662 pp.


HOWARD, H.

   1929.  The avifauna of the Emeryville shellmound. Univ. California
          Publ. Zool., 32:301-394, 3 pls., 54 figs.


HUDSON, G. E.

   1937.  Studies on the muscles of the pelvic appendage in birds.
          Amer. Mid. Nat., 18:1-108, 26 pls.


IRWIN, M. R.

   1953.  Evolutionary patterns of antigenic substances of the blood
          corpuscles in Columbidae. Evol., 7:31-50.


IRWIN, M. R., and COLE, L. J.

   1936.  Immunogenetic studies of species and of species hybrids in
          doves, and the separation of species-specific substances in
          the backcross. Jour. Exp. Zool., 73:85-108, 1 fig.


LEONE, C. A.

   1949.  Comparative serology of some brachyuran crustacea and
          studies in hemocyanin correspondence. Biol. Bull.,
          97:273-286, 3 figs.

   1953.  Some effects of formalin on the serological activity of
          crustacean and mammalian sera. Jour. Immun., 70:386-392,
          2 figs.


LIBBY, R. L.

   1938.  The photronreflectometer--an instrument for the measurement
          of turbid systems. Jour. Immun., 34:71-73, 1 fig.


MARTIN, E. P., and LEONE, C. A.

   1952.  Serological relationships among domestic fowl as shown by
          comparisons of protein preparations from corresponding organ
          systems. Trans. Kansas Acad. Sci., 55:439-444, 1 fig.


MCGIBBON, W. H.

   1945.  Further division of contrasting antigens in species hybrids
          in ducks. Genetics, 30:252-265.


SASAKI, K.

   1928.  Serological examination of the blood-relationship between
          wild and domestic ducks. Jour. Dept. Agri., Kyushu Imp.
          Univ., 2:117-132.


SIMPSON, G. G.

   1944.  Tempo and mode in evolution. Columbia Univ. Press, New York,
          xviii + 237 pp., 36 figs.


SUSHKIN, P. P.

   1924.  [On the Fringillidae and allied groups.] Bull. British
          Ornith. Club, 45:36-39.

   1925.  The evening grosbeak (Hesperiphona), the only American genus
          of a Palaearctic group. Auk, 42:256-261, 2 figs.


TORDOFF, H. B.

   1954.  A systematic study of the avian family Fringillidae, based
          on the structure of the skull. Univ. Michigan Mus. Zool.
          Misc. Publ. No. 81:1-42, 77 figs.


WETMORE, A.

   1951.  A revised classification for the birds of the world.
          Smithsonian Misc. Coll., 117(4):1-22.


_Transmitted June 8, 1954._


25-4632




UNIVERSITY OF KANSAS PUBLICATIONS

MUSEUM OF NATURAL HISTORY


Institutional libraries interested in publications exchange may obtain
this series by addressing the Exchange Librarian, University of Kansas
Library, Lawrence, Kansas. Copies for individuals, persons working in
a particular field of study, may be obtained by addressing instead the
Museum of Natural History, University of Kansas, Lawrence, Kansas.
There is no provision for sale of this series by the University
Library which meets institutional requests, or by the Museum of
Natural History which meets the requests of individuals. However,
when individuals request copies from the Museum, 25 cents should
be included, for each separate number that is 100 pages or more
in length, for the purpose of defraying the costs of wrapping and
mailing.

 * An asterisk designates those numbers of which the Museum's supply
 (not the Library's supply) is exhausted. Numbers published to date,
 in this series, are as follows:

 Vol. 1.  1. The pocket gophers (Genus Thomomys) of Utah. By Stephen D.
             Durrant. Pp. 1-82, 1 figure in text; August 15, 1946.

          2. The systematic status of Eumeces pluvialis Cope, and
             noteworthy records of other amphibians and reptiles from
             Kansas and Oklahoma. By Hobart M. Smith. Pp. 85-89.
             August 15, 1946.

          3. The tadpoles of Bufo cognatus Say. By Hobart M. Smith.
             Pp. 93-96, 1 figure in text. August 15, 1946.

          4. Hybridization between two species of garter snakes.
             By Hobart M. Smith. Pp. 97-100. August 15, 1946.

          5. Selected records of reptiles and amphibians from Kansas.
             By John Breukelman and Hobart M. Smith. Pp. 101-112.
             August 15, 1946.

          6. Kyphosis and other variations in soft-shelled turtles.
             By Hobart M. Smith. Pp. 117-124, 3 figures in text.
             July 7, 1947.

         *7. Natural history of the prairie vole (Mammalian Genus
             Microtus). By E. W. Jameson, Jr. Pp. 125-151, 4 figures in
             text. October 6, 1947.

          8. The postnatal development of two broods of great horned
             owls (Bubo virginianus). By Donald F. Hoffmeister and
             Henry W. Setzer. Pp. 157-173, 5 figures in text.
             October 6, 1947.

          9. Additions to the list of the birds of Louisiana. By George
             H. Lowery, Jr. Pp. 177-192. November 7, 1947.

         10. A check-list of the birds of Idaho. By M. Dale Arvey.
             Pp. 193-216. November 29, 1947.

         11. Subspeciation in pocket gophers of Kansas. By Bernardo
             Villa R. and E. Raymond Hall. Pp. 217-236, 2 figures in
             text. November 29, 1947.

         12. A new bat (Genus Myotis) from Mexico. By Walter W.
             Dalquest and E. Raymond Hall. Pp. 237-244, 6 figures in
             text. December 10, 1947.

         13. Tadarida femorosacca (Merriam) in Tamaulipas, Mexico.
             By Walter W. Dalquest and E. Raymond Hall. Pp. 245-248,
             1 figure in text. December 10, 1947.

         14. A new pocket gopher (Thomomys) and a new spiny pocket
             mouse (Liomys) from Michoacan, Mexico. By E. Raymond Hall
             and Bernardo Villa R. Pp. 249-256, 6 figures in text.
             July 26, 1948.

         15. A new hylid frog from eastern Mexico. By Edward H. Taylor.
             Pp. 257-264, 1 figure in text. August 16, 1948.

         16. A new extinct emydid turtle from the Lower Pliocene of
             Oklahoma. By Edwin C. Galbreath. Pp. 265-280, 1 plate.
             August 16, 1948.

         17. Pliocene and Pleistocene records of fossil turtles from
             western Kansas and Oklahoma. By Edwin C. Galbreath.
             Pp. 281-284. August 16, 1948.

         18. A new species of heteromyid rodent from the Middle
             Oligocene of northeastern Colorado with remarks on the
             skull. By Edwin C. Galbreath. Pp. 285-300, 2 plates.
             August 16, 1948.

         19. Speciation in the Brazilian spiny rats (Genus Proechimys,
             Family Echimyidae). By Joao Moojen. Pp. 301-406,
             140 figures in text. December 10, 1948.

         20. Three new beavers from Utah. By Stephen D. Durrant and
             Harold S. Crane. Pp. 407-417, 7 figures in text.
             December 24, 1948.

         21. Two new meadow mice from Michoacan, Mexico. By E. Raymond
             Hall. Pp. 423-427, 6 figures in text. December 24, 1948.

         22. An annotated check list of the mammals of Michoacan,
             Mexico. By E. Raymond Hall and Bernardo Villa R.
             Pp. 431-472, 2 plates, 1 figure in text. December 27, 1949.

         23. Subspeciation in the kangaroo rat, Dipodomys ordii.
             By Henry W. Setzer. Pp. 473-573, 27 figures in text,
             7 tables. December 27, 1949.

         24. Geographic range of the hooded skunk, Mephitis macroura,
             with description of a new subspecies from Mexico.
             By E. Raymond Hall and Walter W. Dalquest. Pp. 575-580,
             1 figure in text. January 20, 1950.

         25. Pipistrellus cinnamomeus Miller 1902 referred to the Genus
             Myotis. By E. Raymond Hall and Walter W. Dalquest.
             Pp. 581-590, 5 figures in text. January 20, 1950.

         26. A synopsis of the American bats of the Genus Pipistrellus.
             By E. Raymond Hall and Walter W. Dalquest. Pp. 591-602,
             1 figure in text. January 20, 1950.

         Index. Pp. 605-638.

 *Vol. 2.    (Complete) Mammals of Washington. By Walter W. Dalquest.
             Pp. 1-444, 140 figures in text. April 9, 1948.

 Vol. 3. *1. The avifauna of Micronesia, its origin, evolution, and
             distribution. By Rollin H. Baker. Pp. 1-359, 16 figures
             in text. June 12, 1951.

         *2. A quantitative study of the nocturnal migration of birds.
             By George H. Lowery, Jr. Pp. 361-472, 47 figures in text.
             June 29, 1951.

          3. Phylogeny of the waxwings and allied birds. By M. Dale
             Arvey. Pp. 473-530, 49 figures in text, 13 tables.
             October 10, 1951.

          4. Birds from the state of Veracruz, Mexico. By George H.
             Lowery, Jr., and Walter W. Dalquest. Pp. 531-649,
             7 figures in text, 2 tables. October 10, 1951.

          Index. Pp. 651-681.

 *Vol. 4.    (Complete) American weasels. By E. Raymond Hall. Pp. 1-466,
             41 plates, 31 figures in text. December 27, 1951.

 Vol. 5.  1. Preliminary survey of a Paleocene faunule from the Angels
             Peak area, New Mexico. By Robert W. Wilson. Pp. 1-11,
             1 figure in text. February 24, 1951.

          2. Two new moles (Genus Scalopus) from Mexico and Texas.
             By Rollin H. Baker. Pp. 17-24. February 28, 1951.

          3. Two new pocket gophers from Wyoming and Colorado.
             By E. Raymond Hall and H. Gordon Montague. Pp. 25-32.
             February 28, 1951.

          4. Mammals obtained by Dr. Curt von Wedel from the barrier
             beach of Tamaulipas, Mexico. By E. Raymond Hall.
             Pp. 33-47, 1 figure in text. October 1, 1951.

          5. Comments on the taxonomy and geographic distribution of
             some North American rabbits. By E. Raymond Hall and Keith
             R. Kelson. Pp. 49-58. October 1, 1951.

          6. Two new subspecies of Thomomys bottae from New Mexico and
             Colorado. By Keith R. Kelson. Pp. 59-71, 1 figure in text.
             October 1, 1951.

          7. A new subspecies of Microtus montanus from Montana and
             comments on Microtus canicaudus Miller. By E. Raymond Hall
             and Keith R. Kelson. Pp. 73-79. October 1, 1951.

          8. A new pocket gopher (Genus Thomomys) from eastern Colorado.
             By E. Raymond Hall. Pp. 81-85. October 1, 1951.

          9. Mammals taken along the Alaskan Highway. By Rollin H.
             Baker. Pp. 87-117, 1 figure in text. November 28, 1951.

        *10. A synopsis of the North American Lagomorpha. By E. Raymond
             Hall. Pp. 119-202, 68 figures in text. December 15, 1951.

         11. A new pocket mouse (Genus Perognathus) from Kansas.
             By E. Lendell Cockrum. Pp. 203-206. December 15, 1951.

         12. Mammals from Tamaulipas, Mexico. By Rollin H. Baker.
             Pp. 207-218. December 15, 1951.

         13. A new pocket gopher (Genus Thomomys) from Wyoming and
             Colorado. By E. Raymond Hall. Pp. 219-222.
             December 15, 1951.

         14. A new name for the Mexican red bat. By E. Raymond Hall.
             Pp. 223-226. December 15, 1951.

         15. Taxonomic notes on Mexican bats of the Genus Rhogeessa.
             By E. Raymond Hall. Pp. 227-232. April 10, 1952.

         16. Comments on the taxonomy and geographic distribution of
             some North American woodrats (Genus Neotoma). By Keith R.
             Kelson. Pp. 233-242. April 10, 1952.

         17. The subspecies of the Mexican red-bellied squirrel,
             Sciurus aureogaster. By Keith R. Kelson. Pp. 243-250,
             1 figure in text. April 10, 1952.

         18. Geographic range of Peromyscus melanophrys, with
             description of new subspecies. By Rollin H. Baker.
             Pp. 251-258, 1 figure in text. May 10, 1952.

         19. A new chipmunk (Genus Eutamias) from the Black Hills.
             By John A. White. Pp. 259-262. April 10, 1952.

         20. A new pinon mouse (Peromyscus truei) from Durango, Mexico.
             By Robert B. Finley, Jr. Pp. 263-267. May 23, 1952.

         21. An annotated checklist of Nebraskan bats. By Olin L. Webb
             and J. Knox Jones, Jr. Pp. 269-279. May 31, 1952.

         22. Geographic variation in red-backed mice (Genus
             Clethrionomys) of the southern Rocky Mountain region.
             By E. Lendell Cockrum and Kenneth L. Fitch. Pp. 281-292,
             1 figure in text. November 15, 1952.

         23. Comments on the taxonomy and geographic distribution of
             North American microtines. By E. Raymond Hall and
             E. Lendell Cockrum. Pp. 293-312. November 17, 1952.

         24. The subspecific status of two Central American sloths.
             By E. Raymond Hall and Keith R. Kelson. Pp. 313-317.
             November 21, 1952.

         25. Comments on the taxonomy and geographic distribution of
             some North American marsupials, insectivores, and
             carnivores. By E. Raymond Hall and Keith R. Kelson.
             Pp. 319-341. December 5, 1952.

         26. Comments on the taxonomy and geographic distribution of
             some North American rodents. By E. Raymond Hall and Keith
             R. Kelson. Pp. 343-371. December 15, 1952.

         27. A synopsis or the North American microtine rodents.
             By E. Raymond Hall and E. Lendell Cockrum. Pp. 373-498,
             149 figures in text. January 13, 1953.

         28. The pocket gophers (Genus Thomomys) of Coahuila, Mexico.
             By Rollin H. Baker. Pp. 499-514, 1 figure in text.
             June 1, 1953.

         29. Geographic distribution of the pocket mouse, Perognathus
             fasciatus. By J. Knox Jones, Jr. Pp. 515-526, 7 figures in
             text. August 1, 1953.

         30. A new subspecies of wood rat (Neotoma mexicana) from
             Colorado. By Robert B. Finley, Jr. Pp. 527-534, 2 figures
             in text. August 15, 1953.

         31. Four new pocket gophers of the genus Cratogeomys from
             Jalisco, Mexico. By Robert J. Russell. Pp. 535-542.
             October 15, 1953.

         32. Genera and subgenera of chipmunks. By John A. White.
             Pp. 543-561, 12 figures in text. December 1, 1953.

         33. Taxonomy of the chipmunks, Eutamias quadrivittatus and
             Eutamias umbrinus. By John A. White. Pp. 563-582,
             6 figures in text. December 1, 1953.

         34. Geographic distribution and taxonomy of the chipmunks of
             Wyoming. By John A. White. Pp. 584-610, 3 figures in text.
             December 1, 1953.

         35. The baculum of the chipmunks of western North America.
             By John A. White. Pp. 611-631, 19 figures in text.
             December 1, 1953.

         36. Pleistocene Soricidae from San Josecito Cave, Nuevo Leon,
             Mexico. By James S. Findley. Pp. 633-639. December 1, 1953.

         37. Seventeen species of bats recorded from Barro Colorado
             Island, Panama Canal Zone. By E. Raymond Hall and William
             B. Jackson. Pp. 641-646. December 1, 1953.

         Index. Pp. 647-676.

 *Vol. 6.    (Complete) Mammals of Utah, _taxonomy and distribution_.
             By Stephen D. Durrant. Pp. 1-549, 91 figures in text,
             30 tables. August 10, 1952.

 Vol. 7. *1. Mammals of Kansas. By E. Lendell Cockrum. Pp. 1-303,
             73 figures in text, 37 tables. August 25, 1952.

          2. Ecology of the opossum on a natural area in northeastern
             Kansas. By Henry S. Fitch and Lewis L. Sandidge.
             Pp. 305-338, 5 figures in text. August 24, 1953.

         3. The silky pocket mice (Perognathus flavus) of Mexico.
            By Rollin H. Baker. Pp. 339-347, 1 figure in text.
            February 15, 1954.

         4. North American jumping mice (Genus Zapus). By Philip H.
            Krutzsch. Pp. 349-472, 47 figures in text, 4 tables.
            April 21, 1954.

         5. Mammals from Southeastern Alaska. By Rollin H. Baker and
            James S. Findley. Pp. 473-477. April 21, 1954.

         6. Distribution of Some Nebraskan Mammals. By J. Knox Jones.
            Pp. 479-487. April 21, 1954.

         7. Subspeciation in the montane meadow mouse, Microtus
            montanus, in Wyoming and Colorado. By Sydney Anderson.
            Pp. 489-506, 2 figures in text. July 23, 1954.

         8. A new subspecies of bat (Myotis velifer) from Southeastern
            California and Arizona. By Terry A. Vaughn. Pp. 507-512.
            July 23, 1954.

         9. Mammals of the San Gabriel Mountains of California.
            By Terry A. Vaughn. Pp. 513-582, 1 figure in text,
            12 tables. November 15, 1954.

         More numbers will appear in volume 7.

 Vol. 8.  1. Life History and Ecology of the Five-Lined Skink, Eumeces
             fasciatus. By Henry S. Fitch. Pp. 1-156, 26 figures in
             text. September 1, 1954.

         2. Myology and Serology of the Avian Family Fringillidae,
            a Taxonomic Study. By William B. Stallcup. Pp. 157-211,
            23 figures in text, 4 tables. November 15, 1954.

         More numbers will appear in volume 8.




       *       *       *       *       *


  Transcriber's Notes

  The text presented is essentially that in the original printed
  document with the exception of some minor punctuation changes and
  the typographical correction detailed below. Some of the tables
  split between paragraphs in the original and they were moved and
  the paragraphs restored into one. The captions for Figures 10-13
  and 14-17 were reformatted to enhance readability.


  Empasis Notation

    _Text_  -  Italics

    +Text+  -  Bold


  Typographical Corrections

    Page 187, Table 1 Item 5: Intavenous => Intravenous


       *       *       *       *       *





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