OSTEOLOGY OF BIRDS 



43 



assumes the subcylindrical form, becomes gradually smaller in 

 caliber and articulates distally, as usual, with the ulnar e of the car- 

 pus. As in others of the class, there are but two free bones in the 

 wrist of the adult representatives of this family, viz: the ulnare 

 and radial e, and they have the forms common to most large birds 

 of ordinary structure, and articulate in the usual manner. 



Nothing worthy of especial note appears to characterize the carpo- 

 metacarpals among the Cathartidae, and the bone varies but little 

 among the several species of the family, except in point of size. 

 It is composed of the three metacarpals fused together in the most 

 usual method; the whole being in due proportion with the size of the 

 skeleton of the species. 



On the palmar side of the second metacarpal above, the knob 

 formed by the coossified pent osteon is conspicuous, and this is also- 

 found in Neophron and the Falconidae. 



In all the vultures a bony claw is suspended from the end of 

 pollex digit, and it, too, is also found in like place in many of the 

 Falconidae. Externally, this claw of the pollex in the Cathartidae 

 is covered by a horny sheath, in a manner quite similar to the toes 

 of the foot. It is very large in the condors. 



The second metacarpal supports its usual number of phalanges, 

 the upper one presenting the ulnar expansion, common to this joint 

 in so many birds. It is nonperforated except by pneumatic fora- 

 mina ; this limb in its every bone being most thoroughly pneumatic 

 as has already been pointed out above. 



A phalanx is also freely suspended from the last metacarpal. 

 This is the smallest one in hand, being about half the length 

 of the broad one of the second metacarpal alongside of which it 

 is extended. This sometimes develops a tuberous process from its 

 ulnar border, a feature that becomes quite prominent in Neophron. 



Pelvis and the lower extremity. Viewing the pelvic bone from 

 above as it occurs in the Cathartidae, we find that it is only in 

 Cathartes a. septentrionalis that the ilia fails to 

 meet the superior border of the sacral crista in front. In this vul- 

 ture quite an interspace exists between the ilium and this neural 

 crest of the sacrum upon either side, which amounts to 8 milli- 

 meters at the narrowest place, and the aforesaid spine is flattened 

 out therein. Gyparchus makes the next approach to this condition. 

 Tn all the others of the Cathartidae the ilia meet for a greater or less 

 distance mesiad in this locality, and slope away laterally, being most 

 horizontal in the Turkey buzzard. Upon comparing the dorsal 



