OPBTDU. 



249 



Order SQUAMATA. 



Body lacertiform or anguiform, generally covered with scales, 

 which may be underlain by bony scutes. Limbs, when present, 

 adapted for walking or swimming. Proximal end of quadrate more 

 or less movably articulated to cranium ; lower temporal arcade 

 wanting ; postorbital usually united to postfrontal ; palate more or 

 less open ; and premaxillas frequently united. Vertebrae generally 



Eig. 52. 



Iguana tuberculata. — Left lateral aspect of the cartilage-bones of the pectoral 

 girdle. \. s, scapula ; m.sc, mesoscapula ; gl, glenoid cavity ; cor, cora- 

 coid ; p.cor, precoracoid ; m.cor, mesocoracoid ; for, foramen. 



proccelous ; with neurocentral suture obliterated ; with or without 

 zygosphenes ; and no intercentra. Ribs without uncinate processes : 

 and no true abdominal ribs 1 . But one centrale in the carpus ; and 

 the precoracoid (fig. 52) often well marked. Includes the orders 

 Ophidia, Pythonomorpha, and Lacertilia of most writers. 



Suborder OPHIDIA. 



Body greatly elongated. Alisphenoidal region fully ossified ; no 

 temporal arcade, parietal foramen, or columella; quadrate and 

 palato-maxillary region loosely articulated to skull ; premaxillae 

 more or less aborted ; mandibular rami united by ligament. Ver- 

 tebras with zygosphenes, divisible only into trunk and caudal series ; 

 no sacrum ; no chevrons. No sternum, pectoral girdle or pectoral 

 limb, and only occasionally traces of pelvic girdle and limb. No 

 dermal scutes. 



1 Ossifications in the abdominal parietes occur among the Lacertilia in the 

 Anelytropidce and also in the Rhiptoglossa. 



i 



