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NEW YORK STATE MUSEUM 



its entire length to the last articulated sternal rib." This no doubt 

 occurs upon both sides and corresponds to what we found in 

 Gypogeranus, only the rib is longer in this latter vulturine falcon. 

 Cases of asymmetry no doubt occur among many or all of these 

 various arrangements, as, for example, in the skeleton of M i c r a s - 

 t u r brachypterus at hand, we find six sternal ribs on the 

 left side all meeting the sternum, and but five upon the right, the 

 sixth one articulating with the posterior border of the sternal rib in' 

 front of it. 



Scapular arch, sternum and pectoral limb. All the bones of the 

 shoulder girdle are well developed in the family of birds now under 

 consideration, and none of them are fused one with the other, or 

 with the sternum. There is a very great similarity, both in outline 

 and general appearance of this arch as it exists in the Cathartidae, 

 and to this we may add that when the bones forming it are in situ 

 in the articulated skeleton they present a pattern that not only pos- 

 sesses a common resemblance, but is peculiar to the family, and dif- 

 fers very decidedly from the vultures of the Old World and from 

 the Falconidae. We find in our present subjects that the sternal 

 extremities of the coracoids are very much expanded in a transverse 

 direction, that they touch each other, mesiad, when articulated in the 

 sternal grooves or beds designed for them. These dilated ends are 

 scooped out on their posterior aspects where the pneumatic foramina 

 occur, and roughened, while in front the surface is smooth, convex 

 from side to side, and continuous with the general surface of the 

 shaft. The inferior side is occupied for more than its inner half by 

 the facet for articulation with the sternum ; this is broadest mesiad, 

 narrowing in each bone as we proceed outward. The outer angle is 

 truncate and presents an upturned tip of bone, and a face that is 

 directed outward. Very little shaft can be boasted of by these 

 bones, for no sooner do the fanlike lower ends commence to merge 

 into a shaft, than dilatation immediately sets in again to form the 

 great tuberous heads that constitute the opposite and superior ex- 

 tremities. More of a true shaft exists in Catharista than in any 

 other of these vultures, for the coracoids are proportionately longer 

 in this species; in all it is more or less compressed from before, 

 backward, rounded externally, sharper within, where in each bone 

 it is pierced midway by an elliptical foramen, such as is found in the 

 owls and other birds. This last feature is scarcely perceptible in the 

 Carrion crow. Tn each the facet for the scapula is behind and 

 rather toward the median plane : it is placed transversely upon the 



