PELVIC GIRDLE REPTILIA 



267 



pubic processes (either long rods, or plate-like with expanded ends), 

 extending outwards and forwards, are common. An epipubis 

 (paired in origin and usually persisting as 

 cartilage) is frequently present. A hypoiscbium 

 appears in development, but is lost later. All 

 Cryptodires have a lateral process (postischium) 

 on the hinder side of each ischium. 



Crocodxlia differ from other recent reptiles 

 in the exclusion of the pubis from the acetab- 

 ulum, unless it be that the cartilage (fig. 289) 

 which connects the bone with the pelvis be its 

 basal part. In the earliest crocodile-hke rep- 



FiG. 289. — Side and 

 ventral views of pelvis 

 of Alligator (Wieder- 

 sheim). a, acetabular 

 cartilage; g, last gastra- 

 le; /, ligament; >n, mem- 

 brane between p, pubis 

 and gastralia. 



Fig. 290. — Pelves of Theromorphs: A, Diademon 

 (Broom, 'gs); B, Limnoscelis (Williston, 'ii). a, aceta- 

 bulum; _^,Hschio-pubic fenestra; fo, obturator foramen; 

 il, ilium; is, ischium; p, pubis. 



tiles, the Pseudosuchia, the os pubis forms part of the acetabular 

 wall. Another crocodiHan pecuharity is the perforation of the 

 acetabulum. The ilium, inchned downwards and forwards, is 

 expanded dorsally and articulates with a pair of sacral ribs. The 

 long pubes do not meet, but are connected by a strong membrane 

 which extends from the pelvis to the gastraha. The ischia are strong 

 and meet in a cartilaginous symphysis; each sends an anterior 

 process forwards which bounds the acetabulum below. 



Theromorpha (fig. 290).— The pelvis of these reptiles is primitive in many 

 respects. The ventral bones show less variety than does the ilium. The latter 

 may be rather long and tapering (Dicynodon) recalling the .\nura, or it may 

 expand dorsally into a crest extending the length of several vertebra;. The 

 ilium may be vertical, or inclined forwards or backwards. The crest extends 



