8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I43 



The hearts of the Accipitridae are relatively small, ranging from 

 0.40 to 0.81 percent. The flight muscles of most of them are of 

 moderate size, Chondrohierax and Spizaetus being exceptions. The 

 most striking finding is the relatively small size of the supracoracoideus 

 (only 0.39 to 0.56 percent of the body ) . The legs, except in Elano'ides, 

 are fairly large, and the wings are fairly long. These characteristics 

 indicate good fliers but little ability to sustain activity for long periods, 

 unless by soaring. The muscles of the lower extremities of many 

 hawks are relatively large, and those of the upper extremities are not 

 small. Several hawks are strong fliers, although they frequently soar. 



Pandionidae. — The muscles of the osprey resemble those of the 

 Accipitridae, but the legs are smaller and the heart is larger than in 

 most of the latter. 



Falconidae. — The hearts of falcons are a little larger than those of 

 hawks, ranging from 0.53 percent (Micrastur) to 1. 1 1 percent (Poly- 

 borus). The supracoracoideus is also somewhat larger than in hawks. 

 The wings are narrower in species that are fast fliers. The flight and 

 leg muscles of Micrastur semitorquatus are larger than those of 

 Micrastur ruficollis, while the wings are much smaller; yet the 

 buoyancy index is about the same. 



Cracidae. — In the Cracidae, represented in our study by the chest- 

 nut-winged chacalaca (Ortalis garrula) and the black guan (Chae- 

 mepetes unicolor), the flight muscles are moderately large (23 to 

 26 percent), with the supracoracoideus of fair size (2 to 3 percent). 

 These birds are heavy fliers with wings rather moderate in size (buoy- 

 ancy index, 3.66) and broad (aspect ratio, 1.38 to 1.5 1) ; the leg 

 muscles are large (15.7 to 20 percent), while the heart is small (0.48 

 to 0.62 percent). 



Phasianidae. — The phasianids are very interesting. Three species 

 of quail, natives of widely different parts of the world, possess very 

 large flight muscles (Cotumix, 25.6 percent; Odontophorus, 29.4 per- 

 cent; Colinus, 34.3 percent) and large supracoracoideus (5.66 percent; 

 5.89 percent; 7.16 percent), with a "rest" nearly the size of the latter 

 (4.46 percent; 6.17 percent; 5.53 percent). But the heart of Cotumix 

 is about three times the size of that of the other two species (1.00 per- 

 cent compared to 0.34 percent and 0.38 percent). The lower extremi- 

 ties are large (muscles 12.16 percent, 16.38 percent, and 14.6 percent), 

 but the wings are small (buoyancy indices, 2.38, 3.10, 2.62). It should 

 be noted that the aspect ratio of Cotumix is higher than that of other 

 phasianids (2.15 as compared with 1.56 and 1.74). The powerful 

 musculature for flight indicates great bursts of speed although the 



