38 NATURAL HISTORY. [uPPER FLOOR. 
Bipes {Pygopus cariococcd)^ has the tympanum hid under 
the skin^ whilst in the New Holland species^ Fraser’s Bipes 
{Delma), the ears are as distinct as in the Seines. 
The Blind-worms (Angues) have scales like the Scincs> 
but only rudiments of legs concealed beneath the skin. 
Cases 6—13 contain the Serpents^ animals without 
legSj but with mouths capable of such extraordinary dilata-- 
tion^ in consequence of the peculiar mode by which the 
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, secreted by a large gland situated under the 
eye, into the wound occasioned by the bite of the reptile. 
The fangs, when at rest, are concealed by a fold in the 
gums, and behind them are the rudiments of other fangs, to 
replace the former, if lost. The maxillary bones are small 
and carry only the fangs, but there are two rows of pala¬ 
tine 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 carinated, 
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 
are divided into several groups according to the structure 
of the tail, which, in the True Rattle-Snakes (CroiaVi) 
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 Battle-Snake, but 
the tail ends in a small recurved spine : these are all pe¬ 
culiar 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), 
