146 



C. W. Andrews — On the Pelvis of CryptocUdus. 



separated from the inner portion by a notch. This process is also 

 present in Muranosaurus, in which, however, it is much less 

 prominent and does not stand out beyond the level of the acetabulum 

 to nearly the same extent ; it appears to be homologous with the 

 lateral pubic process (ectopubis of Baur) of the chelonian pubis. 



Pelvis of CryptocUdus oxoniensis (Phillips) from above, from the Oxford Clay, 

 Fletton, near Peterborough, pu. pubis ; is. ischium ; it. ilium. One-seventh 

 natural size. 



The symphysial surface is much shorter than in Muranosaurns, 

 but at the same time much deeper. It is spindle-shaped, about 

 16 cm. long and 6 deep, the bone being very thick at this point. 

 The curvature of the symphysial border shows that the two pubes 

 were only in actual contact (if at all) at one point, in front of and 

 behind which they were separated by wedges of cartilage. The 

 anterior cartilage (epipubic) was probably small and continuous 

 with that fringing the anterior border ; while the posterior was 

 thick and no doubt continuous with that between the anterior ends 

 of the ischia, which were separated from the pubes by an interval 

 of about 2 cm. This median bar of cartilage, which divided the 

 foramina obturatoria and most likely persisted even in the oldest 

 individuals, corresponds with the similarly situated cartilage 

 (mesogastroid of Baur) in many chelonian pelves. 



The concave posterior border thickens gradually from within 

 outwards to the ischial surface. This latter is nearly semicircular, 

 the diameter of the semicircle forming the line of division between 

 it and the acetabular surface, the length of which from before 

 backwards is about 8 cm. 



Ischium. — The ischium is of the usual hatchet shape. The anterior 

 portion of its median border is thick and bears a spindle-shaped 

 surface for the cartilage of the symphysis ; behind this the bone 



