OSTEOLOGY OF BIRDS 



45 



tcbra supports a hypapophysial process below. It is best developed 

 in Gymnogyps, where it possesses lateral wings and upon its 

 anterior face bears a small facet for articulation with a similar 

 process upon the centrum of the last dorsal vertebra. 



In the condors, this platelike, laterally compressed hypapophysis, 

 coossified as it is with the lesser one of the vertebra next behind, 

 with its centrum also compressed and deep, gives to the anteroin- 

 ferior portion of this bone a very odd appearance not enjoyed by 

 the pelvis of the other species. For instance, no such feature is 

 present in Neophron, an Old World vulture that agrees more or 

 less with the Falconidae in this particular. The double foramina 

 for the exit of the sacral nerves are present upon the sides of the 

 midsacral vertebrae, and present nothing worthy of special notice; 

 they are as we find them in most birds. 



Passing to an under view of the pelvis, we observe that anteriorly 

 some five or six of the leading sacral vertebrae throw out their 

 lateral processes to abut against the nether surface of the ilium 

 upon either side; and that in the " basin of the pelvis" the para- 

 pophyses are at first thrown out as braces opposite the acetabular 

 where they are of some length, and that thereafter this feature is 

 continued, only the processes progressively shorten to include the 

 last sacral vertebra, where they are the shortest. This arrangement 

 is entered into by the last five (Gymnogyps, Cathartes, Catha- 

 rista) or six (Gyparchus) sacral vertebrae, being effected by a 

 fusion of the outer extremities of the par- and diapophyses, their 

 common margin infringing upon the mesial border of the ilium 

 upon either side. The " pelvic basin " is very commodious and deep, 

 more particularly in the condors and in Catharista ; and this depth 

 is much enhanced by a sort of reduplication forward that takes 

 place from the posterior and united portions of the ilia and ischia, 

 forming a concave recess on either side just within the ischiadic 

 foramen. 



Upon a lateral view of the pelvis, we find the acetabular ring 

 nearly circular, the peripheries of the inner and outer boundaries 

 coming nearest together in their upper and anterior arcs while at 

 their posterior and upper arcs they form the outline of an extensive 

 antitrochanter, whose surface is directed forward, downward, and 

 outward. The greatest amount of surface for the articulation of 

 the femoral head, between the internal and external ring, is found 

 anteriorly and below. A stout osseous pillar separates the cotyloid 

 ring from the much larger and subelliptical ischiac vacuity, which 



