418 



LOWER VERTEBRATES. 



The genus Cydura 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 

 Cyclura, 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 sacr.al region, where 

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

 about two dozen spiniferous branches, which e.\tend as rings completely around the 

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



Fig. :;41. — Cyclwa lophumu, great iguaiiii. 



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

 dorsal crest along the najje considerably elong.ated, though they soon diminish in size, 

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

 tailed lizard described by Shaw in 1802. It is a r.are anim.al, inliabiting Lower Cali- 

 fornia. C. lojyhoma is the great 'igu.ana' of eastern Jamaica, and is ]irovided with 

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

 genus Irpiana, this .animal spends most of its time, during the warmer portions of tlie 

 d.aj', lying out on the sunny branches of some tree. 



The r,ange of liasiliscus extends northward into southern Mexico. In novelty 

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



