SAURIA. 



FAM. IGUAXIDAE. 



The roup of which we are now to speak, is one which embraces 

 numerous genera and species, largely represented in the collection 

 made by the Expedition. 



The characters by which it may be distinguished from the other 

 Saurians, consist in the exclusive presence of scales, either smooth or 

 carinated, imbricated or not imbricated, covering the entire body, 

 limbs, and tail, and, in most cases, provided with a dorsal crest, more 

 or less developed : the abdomen being protected by scales similar in 

 shape and structure to those of the back, instead of those large, sub- 

 quadrangular plates, or scutellae, observed in the Crocodiles, Varanids, 

 and others. The body itself is either compressed or depressed. The 

 upper surface of the head exhibits small, polygonal plates, instead of 

 large shields, or small, granular scales. The maxillary teeth are not 

 driven into the bones, but placed either in a groove or common socket, 

 else soldered to the edge of the bones themselves. The palate is 

 either toothed or toothless. The tongue is thick, depressed, fungous ; 

 its surface is velvet-laced, its apex free, and not retractile into a 

 sheath ; the eyes being large, protected by movable lids. The auricu- 

 lar apertures are generally present, and wanting in a few genera. The 

 fingers and toes are always free, distinct, not palmated, all of which 

 provided with a claw or nail. 



SYN. lyuanoides, OPPEL, Reptil. Prodr. 1811. 



Iguaniens, Cuv. Regn. Anim. II, 1817, 29 ; 2d ed. II, 1829, &, ed. illustr. Kept. 

 46. BUM. & BIBR. Erpe-t. gen. IV, 1827, 1. 



Iguanina, BONAP. Sagg. Distr. Anim. Vertebr. 1830. 



Stellionina, BONAP. Saggio, Dist. Anim. Vertebr. 1830. 



Stellionidae, BONAP. Sagg. Distr. Anim. Vertebr. 1830. 



lyuanidae, GRAY, Synops. Brit. Mus. 1840 ; &, Catal. Lizz. Brit. Mus. 1845, 178. 



Eunotes, DUM. & BIBR. Erpet. gen. IV, 1837, 1. 



Stelliones, FITZ. Syst. Kept. I, 1843. 



The family of Iguanids, as above characterized, is subdivided into 

 two natural groups or subfamilies, according as to whether the teeth 

 are received into a common groove upon the edge of the jaws, or else 

 strongly soldered to these very bones : the representatives of the 

 former inhabit the Old World ; those of the latter, the New World. 



