142 
LIZARDS. 
We have not hitherto mentioned that the vertebrae of the 
Extinct Iguanas. ^ uano p} ]j zar( p s differ from those of the agamoids and most other 
members of the suborder in being furnished with additional articular facets like 
those of snakes. Vertebrae 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 vertebrae 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 
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 
cornutum ) 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 
