206 Mr. Bell on a new Genus oflguanidoe. 



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. Igl'Anid^. Mihi. 

 Genus. Amblyrhynchus. 



Char. G(MT. 



Caput breve, truncaiutn, supra tuberculatum. 

 Gula edentula. 



Cervix, dorsum atque cauda, denticulato-cristatce . 

 Digiti simplices. 



Head short, truncated, tuberculated above. 

 Throat without spines. 

 Neck, back, and tail with a spiny crest. 

 Toes simple. 



Ambly'rhynchus crtstatus. 



Habitat in Mexico. 

 Mus. nostr. 



Icon. Tab. Supp. XII. 



Sent from Mexico by Mr. Bullock, junior. 



DESCUIPTION. 



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 



