Part 2

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.