external ones for canines j behind these there is a series of molar teeth
with compressed triangular and tricuspid crowns, the median cusp
being much the largest of the three : these teeth increase in size
towards the back part of the jaws.
GECKOTIANS.
101 • In this family of nocturnal insectivorous Lizards the teeth are
more pointed, more slender, more equable and more numerous than
in the preceding group. The summit of the tooth is always simple :
the base is obliquely soldered to the internal surface of an outer
alveolar parapet.
In the smooth Gecko (Thecadactylus leevis, PI. 66, fig. 4), there
are about thirty-five such teeth, forming a close-set series on each
side of both jaws; the first five or six above being supported on the
intermaxillary bones, and being rather longer than the rest. In most
of the posterior teeth the crown is slightly expanded, with a trenchant
margin, as shown in fig. 44'; its transverse section is given below. In
the flat-headed Gecko (Ptyadactylus fimbriatus, Cuv.) there are
from seventy to seventy-four teeth on each side. In the House-
Gecko (Ptyadactylus Hasselguistii) the teeth are slightly recurved. In
the common Indian Gecko (Ptyadactylus guttatus, Cuv.) the teeth,
with the exception of a few anterior ones, are rather cylindrical than
conical, and are terminated by obtuse summits. None of the Geckos
have teeth on the roof of the mouth.
IGUANIANS.
102. The lizards of this family are characterized like the preceding
groups by a short contractile tongue, slightly notched at its extremity;
but are distinguished for the most part by having teeth on the pterygoid
bone, and also by the complicated form of the crown of the maxillary
teeth in the typical genera, the species of which subsist
chiefly on vegetable substances.
In most of the Iguanians the teeth are lodged in a common
shallow oblique alveolar groove, and are soldered to excavations on
the inner surface of the outer wall of the groove. MM. Dumeril and
Bibron enumerate the following genera as exhibiting the pleurodont
type of dentition, and as possessing likewise pterygoid teeth: viz.
Polychrus, Urostrophus, Anolis, Corythophanes, Basiliscus, Aploponotus
Amblyrhynchus, Iguana, Metopoceros, Cyclurus, Brachylophus, Leio-
saurus, Hypsibates, Proctotretes, Ecphymotes, Stenocercus and Oplurus.
The following pleurodont genera of Tguanians have no pterygoid
teeth, Hyperanodon, Tropidolepis, Phrynosoma, Callisaurus.
The Acrodont Iguanians include the genera Istiurus, Calotes,
Lophyrus, Otocryptis, and Chlamydosaurus in all of which the maxillary
teeth may be divided into anterior laniary and posterior molary teeth.
In the crested Istiurus. of Amboina the four anterior simple
conical teeth m both upper and lower jaws are very small and represent
incisors ; the six following teeth, three on each side, are larger,
more sharply pointed and incurved; they are followed by thirteen
molars with compressed, triangular, trenchant, but undivided crowns,
which gradually increase in size as they are placed backwards ; the
posterior ones being strong teeth, separated by intervals.
In the blue Calotes may be distinguished five incisors in the
intermaxillary bone, a median and two shorter ones on each side ; a
single long laniary and eighteen or nineteen tricuspid molars on each
side of the upper jaw. In the lower jaw there are two canines on
each side.
The molars are more close-set and numerous in the Lophyri
there being sometimes twenty on each side, these cuspid. are obtusely triIn
the Otocrypt (Otocryptis bivittata) the intermaxillary bones
each support a single tooth, which is conical and straight; the third in
succession, in the superior maxillary bone, is a very large laniary, with
a slightly recurved point. Of the twelve molars which succeed these,
t e anterior are small, simple and compressed; they increase in size
and complexity as they recede backwards, the large posterior molars
anadv isnigm tphlree efo lromb.es, but the series is terminated by teeth of small size
The Chlamydosaurus presents a similar dentition, but the teeth
are relatively larger, and a greater proportion terminates in simple and
pointed summits.
. In the pleurodont Iguanians the teeth never present the true
aniary form; and if simply conical, as at the extremes of the maxillary
R