418 



LOWER VERTEBRATES. 



The genus Cyclura was distinguished as early as 1825, when it was applied to 

 those lizards which have a general resemblance to the iguanas ; three species are now 

 known to inhabit the peninsula of Lower California. C. teres, the smooth-backed 

 Oyclura, has a length of about twenty inches, and is of a general dark-green color 

 Like others of the genus it has a loose fold of skin below its throat, a structure 

 that is maintained by some to be indicative of an irritable disposition. The comb-like 

 spines appear as a low ridge running from the occiput to the sacral region, where 

 after a short interspace, the more prickly caudal crest begins, sending out laterally 

 about two dozen spiniferous branches, which extend as rings completely around the 

 tail, though the spines decrease: in size as they leave the dorsal line. On the inside of 



Fig. 241. — Cyclura Lophuma^ great iguana. 



each thigh is a row of seven glandular orifices. C. hemilopha has the scales of the 

 dorsal crest along the nape considerably elongated, though they soon diminish in size, 

 entirely disappearing at about the middle of the back. O. acanthura is the spine-' 

 tailed lizard described by Shaw in 1802. It is a rare animal, inhabiting Lower Cali- 

 fornia. C. lophoma is the great 'iguana' of eastern Jamaica, and is provided with 

 an elongated dorsal crest like the teeth of a saw. Like the lizards of the related 

 genus Iguana, this animal spends most of its time, during the warmer portions of the 

 day, lying out on the sunny branches of some tree. 



The range of Sasiliseus- extends northward into southern Mexico. In novelty 

 of appearance this animal rivals the Australian ChlamydoaauTus. The basilisk proper 



