206 Mr. Bell on a new Genus of Iguanidoe, ' 



natural and most important group amongst the Saurian reptiles, its 

 structure is such as to demand for it a more distinct place, than 

 that of a mere species of the typical genus; and this will be 

 readily conceded when the structure of the head is particularly 

 remarked, which differs so totally from that of any other in- 

 dividual of the family, as to point out some important deviation 

 in its food. 



Familia. Ic;uanid/E. Mihi, 

 Genus. Amblyrhynchus. 



Char. Gen. 



Caput breve^ iruncatum^ supra tuberculatum, 

 Gula edentula. 



Cervix, dorsum atque cauda, denticulato'cristatce. 

 Digit! simplices. 



Head short, truncated, tuberculated above. 

 Throat without spines. 

 Neck, back, and tail with a spiny crest. 

 Toes simple. 



Amblyrhynchus cristatus. 



Habitat in Mexico. 

 Mus. nostr. 



Icon. Tab. Supp. XII. _ 



Sent from Mexico by Mr. Bullock, junior. 



DESCRIPTION. 



The head is very short and truncated. It is covered above 

 with large, subacute, and prominent tubercles, somewhat sym- 

 metrically arranged, of which those just anterior to the vertex 

 are the longest. The vertical scale is depressed and flat, sur- 

 rounded by a circle of small tubercles. The muzzle is rounded, 

 and so obtuse that the outline of the whole head in front, from 

 ear to ear, forms little more than a semicircle, and is about as 

 high as it is long and wide. The teeth are numerous, and in- 

 stead of being minutely serrated at the edges as in the true 



