Il8 Bulletin of Laboratories of Denison University voi. xi.] 
tected stations. They also have the camelion-like power of 
adapting themselves in a short time to the color of the back- 
ground. 
LACERTILIA. 
The lizards may be distinguished from the recent families 
of reptiles by their scaly bodies, the presence of limbs, the 
absence of a carapace, the three-chambered heart, the fact that 
the jaw is not dislocatable from its cranial attachment as in 
snakes or, more technically, by the following characters : quad- 
rate bone articulated with the skull, parts of the ali- and orbito- 
sphenoid regions fibro-cartilaginous, rami of the madible united 
by a suture, anal cleft transverse, copulatory organs paired. 
KEY TO THE FAMILIES DESCRIBED. 
I. Eyes with movable lids. 
a. Pupil elliptical, vertical ; head without large plates, its 
skin freely movable, . . Eublephatidae . 
aa. Pupil round ; top of head with immovable plates, 
b. A series of femoral pores. 
c. Lateral scales not abruptly smaller than the ventrals 
in numerous series ; tongue not deeply divided, 
Iguanidae. 
cc. Lateral scales granular like the dorsals and smaller 
than the ventrals, which are in 8 longitudinal 
series, tongue ending in two slender points, 
Teiidae. 
bb. No femoral pores. 
d. Lateral scales very much smaller than the dorsal and 
ventral, usually hidden by a lateral fold; dorsal 
scales keeled, .... Anguidae. 
dd. Lateral scales not much smaller than dorsals and 
ventrals ; no lateral fold ; scales smooth, 
e. Scales on body flat, thin and imbricate, Scincidae. 
ee. Scales tuberculate, usually bony, with granular 
interspaces. Poison glands present, Helodennidae. 
II. Eyes without lids ; pupil elliptical, . Xantusiideay 
