249 



Family IV. ILYSIID^E. 



Cranial bones solidly united ; transpalatine present ; pterygoids 

 extending to quadrate ; suprateuiporal very small and wedged in 

 between the adjacent bones ; quadrate very short ; praefroutals 

 forming a suture with nasals. Mandible with coronoid bone. 

 Teeth in jaws and on palate. Vestiges of pelvis, formed of three 

 or four elements, as in the Boidw, and terminating in a claw-like 

 spur usually distinguishable on each side of the vent. 



This family forms a passage from the Boidce to the Uropeltidce, 

 agreeing with the latter in the physiognomy and scaling, witli 

 the former in the presence of vestiges of pelvis, whilst the skull 

 is exactly intermediate. 



Only two genera are known, the South-American Ilysia and 

 the East-Indian Cylindropliis. 



pm, 



ar. Articular. 

 bo. Basioccipital. 

 cor. Coronoid. 



d. Dentarv. 

 co. Exoccipital. 



/. Frontal. 



Fig. 77. Skull of Cylinclrophis rufus. 



m. Maxillary. pt. Pterygoicl. 



n. Nasal. q. Quadrate. 



p. Parietal. so. Supraoccipital. 



pm. Praemaxillary. st. Supratemporal. 



prf. Prsefrontal. tp. Transpalatine. 

 pro. Prootic. 



Genus CYLINDROPHIS, 

 Wagler, Icon. Amph., 1828. 



Teeth moderate, subequal, 10 to 12 in each maxillary ; none in 

 praemaxillary. Head not distinct from neck ; eye very small, with 

 round or vertically subelliptical pupil, distinct from the neighbouring 

 shields ; a mental groove ; head with large symmetrical shields * ; 



* For the terms applied to the shields of the head, see fig. 87, p. 278. 



