NATURAL HISTORY. 
41 
ROOM X.] 
lower jaw is attached to the cranium, that they are able to 
swallow very large bodies, entire. 
Case 6 contains the pre-eminently poisonous serpents, 
whose upper jaws are furnished with large, moveable fangs, 
having a small groove on the convex edge, for conveying 
the poison (which is secreted by a large gland situated 
under the eye) into the wound occasioned by the bite of 
the reptile. The fangs, when unemployed, are concealed 
by a fold in the gums, and behind them are the rudiments 
of other fangs, to replace the former, if lost. The maxil¬ 
lary bones are small and carry only the fangs, but 
there are two rows of palatine teeth, in the upper part of 
the mouth. The poisonous snakes are distinguished by 
the size of the head, which in general is large, and often 
covered with small scales; by the scales of the body being 
usually rough and keeled, and by the tail being very short, 
and, in most instances, thin in comparison with the body. 
The most deadly of these serpents have a large pit like 
a second nostril on the cheek, just before the eye. They 
have been divided into several groups according to the 
structure of the tail, which, in the True Rattle-Snakes 
(Crolali) ends in a rattle, formed by a series of horny 
joints, fitting one into the other, which the animal can shake 
at pleasure. There are in the Collection several species 
of this genus, and some detached rattles, to shew their 
structure. 
The Tisiphone ( Tisiphone ) is much like the Rattle- 
Snake, but the tail ends in a small recurved spine: these 
are all peculiar to America. Most of the Snakes of this 
division have the tail simple at the end, and are found 
both in the Old and New world. Some of these ( Cophias ), 
have the head covered with scales like those on the back, 
as the Fer de Lance of the French American Colonists 
(Cophias lanceolatus ), from the West India Islands; and 
the Green Cophias ( Cophias viridis ), the Purple-spotted 
Cophias (Cophias purpureo-maculatus), and the Beautiful 
Cophias (Cophias ornatus ). The last three are the most 
beautiful, and the most poisonous snakes of India. 
Other species with simple tails, have the head covered 
with large shield-like plates (Trigonocephali). 
The Vipers have the same broad head as the Rattle- 
Snakes, but have no pit before the eyes, Amongst 
