2 IGUANIDE. 
to aslight degree by one genus only (Uraniscodon) ; in all others 
the teeth are subequal in size, and if, as is usually the case, the 
lateral ones differ from the front ones, the change is gradual. In 
all genera save Amblyrhynchus, Conolophus, and Phymaturus, the 
anterior teeth are conical ; the lateral ones are also sometimes simply 
conical or with obtuse crowns, but more frequently compressed and 
tricuspid ; in Zywana and Metopoceros the crowns are finely den ticu= 
lated on the edge. In the above-named highly remarkable genera 
Amblyrhynchus, Conolophus, and Phymaturus, all the teeth are 
deeply trilobate, or flower-de-luce shaped. The shafts of the teeth 
are constantly long and cylindrical, and hollowed out at the base. 
Pterygoid teeth are present in many species; I have not employed 
this character for the distinction of genera unless accompanied by 
others. Chamveleolis is one of the few Lizards in which teeth are 
inserted on the palatine bones. 
The skull does not differ in any important point from that of the 
Agamide, However, dermal cranial ossifications, as, for instance, 
the horn-like tubercles of Phrynosoma, may be present. A supra- 
orbital arch, such as has been noticed in the Agamoid genus Lyrio- 
cephalus, occurs in Corythophanes and Phrynosoma. The clavicle is 
slender proximally, except in the genera Basiliscus and Lemanctus. 
In describing the Jguania as having the “clavicle with simple 
proximal ends,” Cope* remarks in a footnote that “ the transverse 
limb of the mesosternum [sternum, odis] extending to the angle of 
the clavicle, gives an appearance in some of the Basiliscine of a 
proximal foramen.” I had hitherto held this opinion to be correct, 
but now find, on careful examination of the pectoral arch of the types 
alluded to, that the clavicle is really loop-shaped, and that those two 
genera constitute an exception in the family /guanide, which is cha- 
racterized by a non-dilated clavicle. The interclavicle is T- or anchor- 
shaped, exceptin Phrynosoma, in which the longitudinal limbis absent. 
The sternum is frequently perforated by a fontanelle. A more or 
less complete system of ossified or tendinous abdominal ribs is deve- 
loped in many genera, in some (Anolis, Polychrus, Inosaurus, &c.) 
to the same extent as in the Geckonide. 
The tongue is thick and villose, entirely fixed to the floor of the 
mouth, or slightly free anteriorly, and not or but very feebly nicked. 
The pupil of the eye is round, and the eyelids well developed. The 
tympanum is distinct, except in Holbrookia. 
Femoral pores exist in all North-American genera, and are absent 
in the great majority of the South-American. In some of the 
latter the males have a series of pores on the anterior border of the 
vent, 
The scaling of the head and body varies extremely, and gular 
appendages, crests, and other ornaments are not unfrequent. The 
upper head-scales are usually small, but in some genera assume a 
* Proc. Ac. Philad. 1864, p. 227. 
