OPHIDIA. 
281 
among the Saurians ; a range of pores before the anus ; the teeth few, conical, and growing only from 
the jaw, none from the palate ; and they have only one lung. 
There are three or four species, which live on insects, and are found principally about ant-hills, a circum- 
stance which has induced the opinion that they subsist chiefly upon Ants. They are oviparous. 
The Typhlops {Typhlops, Schneider) — 
Have the body covered with small imbricated scales, like the Orvets, with which they were long 
arranged ; the muzzle prolonged and plated ; the tongue rather long and forked ; the eye reduced to a 
point, scarcely visible through the skin ; the anus nearly at the extremity of the body ; and one lung 
four times as large as the other. They are small species, resembling Earth-worms at the first glance, 
and are found in the hot regions of both continents. 
Some have the head obtuse and even with the body, resembling' packthread at both ends. Others have the 
muzzle depressed and obtuse, with scaly plates anteriorly. Some, again, have the fore-part of the muzzle covered 
with a single broad plate rather sharp in front. And there are others in which the muzzle terminates in a little 
conical point, being also totally blind : the posterior extremity of these is enveloped in a bony oval buckler, and 
they were formerly ranged with the Orvets, on account of their small scales. 
The other tribe, or that of the Serpents properly so called, have a tympanie bone or pedicle to 
the lower jaw, which is moveable, and nearly always suspended by another bone analogous to the 
mastoid, which latter is attached to the skull by muscles and ligaments, that allow it also to be 
moveable. The branehes of this jaw are not united together, and those of the upper are connected by 
ligaments only to the intermaxillaries ; so that they can open more or less, which imparts to these 
animals the capability of dilating the mouth, so as to swallow objects of greater bulk than themselves. 
Their palatal arches partake of this mobility, and are armed with recurved and pointed teeth, 
which is the most mai'ked and constant character of this tribe ; their windpipe is very long ; the 
heart placed far backward ; and the greater number have only one great lung, with the vestige of 
a second. 
They divide into venomous and non-venomous, and the former of these into venomous having 
several maxillary teeth, and into venomous with isolated fangs. 
In the non-venomous, the branches of the upper jaw are furnished throughout their length, like 
those of the lower jaw and the palate, with fixed and solid teeth. There are three or four subequal 
ranges of these teeth in the upper part of the mouth, and two in the low'er.* Those among them 
which have the mastoid bones inclosed within the cranium, the orbit incomplete behind, the tongue 
short and thick, and which resemble the Bouble-Marcheurs in the cylindrical form of their head and 
body, were formerly classed with the Orvets, on account of their diminutive scales. 
The Roles {Tortrix, Oppel ; Torquatrix, Gray; Ilysia, Hemp.), — 
Are externally distinguished from the Orvets by the range of scales along the belly and beneath the 
tail being rather larger than the others, as also by the extreme shortness of the tail. They have but 
one lung. All are from America. 
The Uropeltis, Cuv. (AniUus, Oken), is an allied new genus, the tail of which, still shorter and obliquely trun- 
cated above, is flat and beset with little scales at the truncation. Their head is very small ; the muzzle pointed ; 
they have a range of scales under the tail, a little larger than the rest, and a double range beneath its truncate 
portion. 
The non-venomous Serpents which, on the contrary, have detaehed mastoid bones, and the jaws of 
which are dilatable, have the occiput more or less bulged, and the tongue forked and very extensible. 
Two principal genera have long been distinguished, — the Boas and the Snakes proper. 
The Boas {Boa, Lin.), — 
Formerly comprehended all Serpents, venomous or not so, the under-part of the body and tail of 
which is covered with scaly transverse hands, each of a single piece, and which have neither spur nor 
rattle at the tip of the tail. Being very numerous, it is necessary to subdivide them, after abstracting 
the venomous ones. 
* The common opinion is, that all Serpents destitute of pierced 
fau^s in the lower part of the jaw, are non-venomous ; but this I have 
some reason to doubt. All have a maxillary gland, often very large ; 
and the back-molars frequently exhibit a groove, which would seem to 
conduct some liquor. This much is certain, that various species, the 
back-molars of which are very large, are reputed to be ex'remely 
venomous in the countries which they inhabit; an opinion which is 
confirmed by the experiments of Lalande and Leschenauld, which it 
is desirable should be repeated. 
