154 CLASSIFICATION OF KEPTILES. 



with a sort of helmet or hood^ and a high fin-hke cresi 

 extends along the back and tail of the males. They in- 

 habit the Old '^Forldj while the true Iguanas are confined 

 to the New. These latter are very large Hzards^ of a beau- 

 tiful green colour elegantly varied^ and with a hanging 

 pouch under the throaty which seems analogous to the 

 dev/-lap of the oxen : this pouch can be inflated^ but un- 

 der what circumstances is not exactly known. All the 

 sub-genera have the tail more or less surmounted with 

 spines ; but in the genus PoIycJirus, which next succeeds, 

 the tail is not only simple and round, but is more or less 

 prehensile : thus we see the chameleons represented un- 

 der a different fonu; and having got a representation 

 of the aquatic type, or Emydosaures, in Flatydactylus, we 

 find the scansorial at the other end of the circle, under 

 the form of Polyclirus. The genus which intervenes 

 betw'een the last and that of Flatydactylus, appears to 

 be Anolis, composed of the goitered lizards : we infer 

 this for two reasons ; first, because Norops seems to 

 hold an intervening station between Polychrus and 

 Anolis; and, secondly, because the goitered hzards 

 have a small disk on each of their toes, thereby indi- 

 cating their close relationship to the geckos : they are, 

 however, differently formed in other respects, for they 

 all have an enormous gular pouch, and some of them — 

 perhaps the most typical — have a crest of spines similar 

 to the true Iguanas. To connect these with the geckos, 

 or nocturnal lizards, we make use of the sub-genus Ste- 

 nodactyhis, which evidently is an aberrant form, since the 

 five types of Flatydactylus are all furnished with disks 

 to their toes. Nothing of popular interest, yet known, 

 attaches to these reptiles, and we shall therefore proceed 

 to the next family. 



(157.) The Lacertid^, or slender-tongued hzards, 

 form a less numerous, but a much more elegant family 

 than the last : their head is small, and is not larger in 

 its circumference than the neck ; hence there is no per- 

 ceptible division between the head and body. This struc- 



