106 
NATURAL HISTORY. 
[n. ZOOL. GAL 
deadly snake of the Cape. The Adders ( Beri ) have the head covered 
with granular scales, and the nostrils moderate; and the Ammodyte has 
the end of the nose lengthened into a flexible horn. The common 
Adder ( Coluber chersea ) differs from these, by the crown of the head 
having three larger scales inserted amongst the smaller ones; this is the 
only reptile found in Great Britain possessed of dangerously poisonous 
qualities. 
The Harmless Snakes, ( Ophidia Innocua , Cases 9 to 19,) on the 
contrary, have strong jaws, both furnished with one or more series of 
teeth. The head is of moderate size compared with the body, and its 
crown is covered with large regular shields. These species are, in 
general, innocent; a few have some of the upper lateral teeth rather 
larger than the rest, and grooved on the hinder edge, the groove com¬ 
municating with a gland placed on the side of the face, but their bite is 
seldom so dangerous as that of the eminently poisonous snakes. They 
are divided into three families. 
The family of Colubrlele, ( Cases 9 to 17, ) which contains more than 
half of the species of Snakes, are characterized by having the belly 
covered with broad cross plates, like the Poisonous Serpents. Their 
tail is elongated and conical. Such of them as live on the ground and 
take to the water for protection, or to catch their food, have generally a 
cylindrical form, and a tail scarcely as long as the body; sometimes the 
head is large, and the scales are placed in longitudinal series, as in Co- 
ronella, Lycodon, Tropidonotus , &c. Others differ in having a smaller 
head, smooth scales, and a small frontal plate, as Calamoria , Bungarus , 
and the Coral Snakes (Claps) ; the latter are often marked with alter¬ 
nate black and bright coloured bands, as in daps corallinus; and the 
Fiat-tailed Coral Snake ( Platurus ) found in the Indian Seas, differs 
from the others by its tail being flattened like the Sea- Snakes. Some 
of these, as the Spectacle Snake or Naja, and Sepedon, have a small 
head, and the scales placed in cross bands; the former have the faculty 
of dilating the skin of the neck, so as to form a kind of hood over the 
head. The Indian species have usually a yellow spot on the back of 
the neck, somewhat resembling a pair of spectacles. These snakes are 
used by the native jugglers in their exhibitions. 
Those which live the greater part of their life on trees, and are thence 
called Tree-Snakes, ( Dendrophis ,) are long and slender, and generally 
have the scales on the sides of th 3 back narrow, and longer than those 
on the dorsal line ; in some of these the end of the muzzle is lengthened 
out into an acute appendage (Passerita). The Bull-headed Snakes 
(Dipsas) resemble the Tree-Snakes in form, but the head is short and 
broad, the body compressed, and they have a series of larger scales 
down the back. In the last two groups some fangs are most commonly 
found intermingled with the teeth. 
The family of Boas (Boidjs, Case 18) have usually a short body, 
with narrow plates on the abdomen, and a short conical tail, furnished 
with two short crooked spurs at its base. These spurs have lately been 
shewn to be analogous to the hinder legs of other reptiles. The eyes 
and nostrils are lateral, the former have an elongated oval pupil, and 
the tail is conical and prehensile. The Boas are not venomous; they 
kill their prey by crushing it between the folds of the body, generally, 
