IGUANAS. 109 



Strobilosaura and Nyctisaura of Dr. Gray, or the tribe of the Iguanas 

 and their kindred, and that of the Geckos and their kindred. The 

 tribe of 



Strobilosaura 



Have the scales of the back and sides imbricate, generally rhombic, 

 and those of the lower parts imbricate and of small size. Tail with 

 more or less distinct whorls of scales. The eyes diurnal, with round 

 pupil, and valvular lids. Feet with toes of very unequal length. 

 Many of these Reptiles have a row of spines or spine-like scales along 

 the back and tail, which in some are very long, while others have 

 high dorsal and caudal crests, and an expansile gular pouch. Like 

 the Varans among the Leptoglossa (p. 107), these Lizards do not 

 renew the tail, or a portion of it, after mutilation. There are 

 two great families of them — one peculiar to the Old World and 

 Australia, the other to the New World ; but they do not differ 

 much, and might very well be retained as varieties of the same ex- 

 tensive family. 



In the family of Iguanidce, all of which • inhabit America or its 

 islands, the teeth are round at the root, dilated and compressed at the 

 tip, and toothed at the edge ; they are placed in a simple series on 

 the inner side of the jaws, just below the margin, and are covered on 

 the inner side by the gums ; as they fall out they are replaced by 

 others, which grow at the base of their predecessors. Probably not 

 fewer than 150 species are now recognised, which are distributed 

 under more than fifty genera. We can only notice a few of the 

 most remarkable of these Lizards, some of the larger of which attain 

 a length of five or six feet, with proportionate bulk of body. As 

 a general rule, the larger species are principally herbivorous, while 

 the smaller are generally insectivorous, though many of the latter also 

 devour fruit. As most of them are remarkable for their rapid changes 

 of colour, the name of chameleon is often misapplied to them, in the 

 supposition that the chameleons are the only lizards in which that 

 curious phenomenon is observable. Of one remarkable species, the 

 Sphcerops anomalus, inhabiting Brazil, it is stated that the eye nearly 

 resembles that of the true chameleons, it is also one of those which 

 are particularly celebrated for changing its hue. 



The name Iguana was given by Laurenti to a heterogeneous group 

 of Saurians, various forms being included which were first separated 

 by Daudin. The Iguanas, as thus restricted, are characterised by a 

 very large thin dew-lap under the neck, a double row of small palatal 

 teeth, and a crest on the back and tail ; the latter long, slender, com- 



