142 



LIZARDS. 



Extinct Iguanas. 



We have not hitherto mentioned that the vertebrae of the 

 iguanoid lizards differ from those of the agamoids and most other 

 members of the suborder in being furnished with additional articular facets like 

 those of snakes. Vertebras of this peculiar type occur in the upper Eocene rocks 

 of England and the Continent, and have been provisionally assigned to the typical 

 genus Iguana, although it is more likely that they indicate an extinct genus. 

 Somewhat similar vertebras from the corresponding strata of the United States 

 have been described under the name of Iguanavus. . 



The last and at the same time the most peculiar members of the 

 present family are the horned lizards of North America and Mexico, 

 which may be regarded as the representatives of the moloch lizard among the 

 agamoids. From their short, rounded heads, abbreviated bodies, and shortened 



Homed Lizards. 



horned lizard (f nat. size 



tails, coupled with a general batrachian appearance, these lizards are commonly 

 termed toads in America, the popular name of the figured species (Phrynosoma 

 comutwm) being the Californian toad. Strange, not to say ugly, in appearance, 

 these lizards are at once distinguished from all their allies by the presence of 

 several bony spines projecting from the back of the shortened head, and of tubercles 

 or spines scattered among the ordinary scales of the body. In form, the body is 

 broad and depressed, without any crest down the back; and the tail is very 

 thick at the base, and never longer than the body. The limbs are rather long, 

 with pores on the thighs, and keeled plates on the lower surfaces of the toes. 

 From most other members of the family these lizards are further distinguished 

 by the absence of teeth on the palate. Of the twelve species of the genus the 

 best known is the common horned toad, herewith figured, which has the tail longer 

 than the head, distinct spines on the back, and the drum of the ear naked. Its 

 general appearance is even more than superficially toad-like, the head being as 



