134 DIVISION I. VERTEBRAL ANIMALS.—CLASS III. REPTILIA. 
liquid, secreted by a large gland beneath the eye. It is this liquid which is 
instilled into the wound inflicted by the tooth, that produces the effects more 
or less deadly, according to the species from which it proceeds, 
“ Venomous serpents, with isolated fangs, present nearly the same external 
characters; but the greater number have extremely dilatable jaws, and the 
tongue very extensile. Their head, which is wide posteriorly, has, in gen- 
eral, a savage aspect, which, to a certain extent, announces their ferocity. 
They form two great genera, — the Rattlesnakes and the Vipers.” 
Genus Croratus, Linn. — These snakes, so celebrated for the deadli- 
ness of their venom, are exclusively American. They were formerly very 
numerous in all the Eastern States, but are now nearly exterminated. This 
reptile is one of the most dangerous of its family, its bite, properly inflicted, 
being sure to cause the death of the largest animal. It is totally unknown 
in the Old World, and is readily distinguished by its rattle — an instrument 
situated at the tail extremity, and consisting of several horny, membranous 
eells, which rattle upon each other when agitated by the animal. The Rat- 
tlesnake is of a tawny and black color above, and ash color beneath; has a 
short and rather round head; a large protecting scale over each eye, and 
Jong, sharp-pointed fangs. It is slow in its motions, inactive in its habits, 
and not readily disturbed — features which luckily tend to lessen the mis- 
chief which otherwise it would be capable of inflicting. Its head is broad, 
triangular, and generally flat in its entire extent. Its eyes are very bril- 
liant, and provided with a nictitating membrane, the mouth very large, the 
tongue forked at its extremity. Its body is robust, elongated, cylindrical, 
covered above with carinated scales. Its tail is short, cylindrical, and some- 
what thick. The number of the little bells, which terminate it, increases 
with age, an additional one being formed at every casting of the skin. These 
bells are truncated, quadrangular pyramids, received within each other in 
such a manner that only a third part of each is visible, the tip of every bone 
running within two of the bones below it. Thus they are united by a kind 
of ball and socket joint, and move with a rattling sound whenever the ani- 
mal agitates its tail. The noise resembles that made by rumpled parchment, 
or two quills of a goose rubbed smartly against each other. The poison 
fangs are trayersed by a canal for the emission of the poison. These fangs, 
when not used, remain concealed in a fold of the gum; when the animal 
bites, the fangs are raised. They are two in number, one at each end of 
the upper jaw. The effects of the poison of course depend much upon the 
season of the year, the age, and strength of the reptile, and the part struck ; 
hence numerous cases are on record of individuals recovering in a few weeks 
from the bite of a Rattlesnake. It is also found, by experiment, that the 
effect of subsequent wounds is greatly diminished, either by the diminution 
Sa 
