Manchester Memoirs, Vol. liv. (1909), No. 4 21 



animal was apparently quite adult at death the ischia are 

 noticeably short. 



Ih'a. Both ilia are preserved although no longer 

 attached to the ischia. 



The ilium, although really quite large, appears small 

 and weak when compared with the other bones of the 

 pelvis. 



The acetabular end is of nearly circular transverse 

 section, it bears two faces, the larger for the acetabulum 

 and the other for the ischium. 



This end passes imperceptibly into the blade of the 

 bone, which is flattened, some 10 or 12 cm. across at the 

 top and at the maximum 2 cm. thick. The lower edge 

 is straight, and formed by a sharp ridge, the upper is 

 smooth and strongly concave. The crest is flat and 

 pitted for a cartilaginous extension. The inner face of 

 the bone is flat or almost concave ; the outer side is 

 convex. 



In the diagram the ilia are represented as much fore- 

 shortened and are accidentally reversed. 



Discussion of the Determinatioji of the Specimen. 



Only two Upper Liassic species have been described 

 to which the specimen I have just discussed could belong; 

 these are P. longirostris and P. coelospondylns. 



There are no materials extant for determining what 

 Owen meant by the latter species, which must be 

 dropped. 



The only parts of P. longirostris which can be com- 

 pared with my specimen are : the cervical vertebrse, the 

 length of the dorsal centra, and the relative and actual 

 sizes of the pro-podials. 



Blake's description suggests that in P. longirostris the 

 cervicals are of similar size throughout the neck. 



