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