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room x. Seines, but they are without legs, and have only 
the rudiments of them placed beneath the skin. 
Cases 6— 13 contain the serpents ( Ophidii ), 
animals characterized by the want of legs, and 
having very dilatable mouths, which enable them 
to swallow entire very large bodies. 
Case 6 contains those serpents that are pre¬ 
eminently poisonous, whose upper jaws are 
toothless, but provided with large moveable 
fangs on the palate. These fangs are furnished 
with a groove on the convex edge by which the 
poison, secreted in a bag placed at the root of 
the teeth, is conducted into the wound. The 
poisonous snakes are generally distinguished by 
the large size of their head, often covered with 
small scales; by the scales of the body being 
generally rough and keeled, and by the tail 
being very short, and generally thin in com¬ 
parison with the body. 
The most deadly of these have a large pit 
like a second nostril on the cheek, just before 
the eye. These have been divided into several 
groups according to the structure of the tail. 
Thus, in the True Rattle Snakes ( Crotalus ), 
the tail ends in a rattle formed by a series of 
horny joints, fitting one into the other, which 
shake, and make a rattling noise when the 
animal moves. There are in the Collection, 
several species of this genus, and some rattles, 
separate, to shew their structure. 
The 
