38 SCOTT. [Vol. V. 



VII. The Hind Limb. 



Of the pelvis but little is preserved in any of the specimens. 

 The best is one consisting of the acetabulum, a considerable 

 portion of the ilium, and the base of the ischium ; this specimen 

 is of P. Wilsoni, and belongs to the Museum of Comparative 

 Zoology at Cambridge. The acetabulum is slightly more 

 depressed and less circular than in the existing species and has 

 a somewhat less prominent rim. The ilium is remarkable for 

 its very long, shallow, and compressed peduncle. The fragment 

 is preserved as far forward as the hinder edge of the surface for 

 the attachment of the sacral vertebrae, and for this entire dis- 

 tance the ischial and acetabular borders are nearly parallel, giv- 

 ing to this region of the bone a very different appearance from 

 that which occurs in the recent forms : in the llama the neck 

 of the ilium is especially reduced in length. The expanded 

 plate of the ilium is unfortunately broken away, but it obvi- 

 ously was not very large. The ischium, so far as it is preserved, 

 is also shallow with nearly parallel borders ; it does not show 

 the high, thin, and arched crest, which is so prominent in the 

 llama (but not to the same degree in the camel) above and behind 

 the acetabulum. In the recent species there are above the 

 acetabulum several prominent and rugose ridges for the attach- 

 ment of the deep gluteus muscle, while in Pcebrotherium these 

 are very faintly shown. The pubis, at its origin below the 

 acetabulum, is slender and of trihedral section ; it forms a some- 

 what more open angle with the axis of the ilium than in the 

 camel and llama. 



The femur (PL II, Figs. 38, 39) is characteristically tylo- 

 podan in appearance. Kowalevsky has called attention to the 

 peculiarities of this bone in the Camelidce, " in which the supe- 

 rior end of the femur is shaped on a plan entirely different 

 from other ruminants, presenting a great resemblance to the 

 Imparidigitata {Rhinoceros) in the breadth of the connecting 

 bridge and the shape and position of the great trochanter." 

 (No. 17, p. 30). In Pcebrotherium the proximal end is less 

 expanded laterally than in the living cameline genera ; the head 

 is small and projects less obliquely upward than in Auchenia, 

 but is set upon a somewhat more distinct neck. The pit for the 

 round ligament is an oval depression placed upon the posterior 



