1058 



DR. R. BROOM ON THE ORIGIN 



[Dec. 10, 



have an ilium with a fairly well-marked crest directed mainly 

 backwards, an ischium of the flat semicircular type, and a rounded 

 pubis. It is from some such type as this that all the later pelvic 

 types have spi-ung. In the early Diapsidan reptiles the pelvis is 

 but little modified from the early type. In Procolophon the 

 pubis and ischium are flat and lie in one plane, forming the 

 typical plate-like pelvis. The ilium has a fairly broad crest. In 

 Palceohatteria the pelvis is almost exactly similar, and in a large 

 number of the later Diapsidan orders the same type is retained 

 with little modification. In the Pelycosauria, as exemplified by 

 Embolophonis (25), the pelvis is of the plate-like type, but the 

 ilium differs from the earlier forms in having the crest directed 

 very markedly backwards. 



Text-fi^. 247. 



C B 



Pelvis of Mammal-like Reptiles. 



A. Procolophon trigoniceps, 



B. Galechirus scJioltsi. 



C. Oudenodon trigoniceps. 



D. Diademodon mastacus. 



II., ilium; Is., ischium; Pti., pubis. 



Among the Colytosaurs, and even above the Labyrinthodonts^ 

 the ilium presents a number of modifications in connection with 

 the various habits of the animals. In Eryops the ilium is long 



