266 ZOOLOGY. 
large behind, with a flat crown, which is covered by scales (except in one 
or two genera, which have plates). The belly is covered by broad band- 
like shields, and there are no spurs or rudimentary feet on each side of the 
anus. The species are all more or less venomous, and generally ovo- 
viviparous. , 
The genus Crotalus, or rattlesnake, forms the type of this family, and 
its species are distinguished from all the rest by the presence of a rattle at 
the end of the tail. This consists of several joints of a horny texture 
loosely united together, so that when quickly vibrated a noise is produced 
much like that of peas shaken about in a dried bladder, and bearing a 
considerable resemblance to the sound produced by the locust or cicada. 
There are two or three species of the restricted genus Crotalus in North 
America: one the C. durissus, another the C. adamanteus. The former 
is abundantly distributed throughout the United States, although limited 
in northern extent, and rarely found north of the parallel of 45°; it is espe- 
‘cially common in the Alleghany region of the United States, where its 
habits are familiar to every resident. It is a sluggish animal, and not 
disposed to act on the offensive, so that a person may pass within a few 
feet of it without being molested. An approximation of that kind is 
generally followed by an alarm from the snake, which most usually pre- 
cedes any blow. The animal never strikes except when coiled, and rarely, 
if ever, follows a retreating enemy. Its food consists of small animals, 
rabbits, squirrels, rats, birds, &c., all of which are speedily destroyed by a 
single blow. Even dogs are sometimes killed by them, although larger 
animals are not generally destroyed. The immense Crotalus adamanteus, 
or diamond rattlesnake of the Southern States, is vastly more formidable. 
This species appears restricted to the southern coast below the latitude of 
North Carolina, and has been known to exceed eight feet in length, with a 
thickness equal to that of a stout man’s leg. They keep much about the 
water, and have hence been called the water-rattle, in distinction from the 
preceding species, which affects high dry land. A third species, common 
in South America, is C. horridus, sometimes called Cascavella, and repre- 
sented in pl. 87, fig. 5. There are also several small species in North 
America belonging to an allied genus Crotalophorus, and usually termed 
ground rattlesnakes. These have the head covered with plates, and the 
rattles very small, even in individuals of considerable size. One of the 
species, called the Massasauga, occurs in Northern Ohio, others in the 
Southern States, and.in the region west of the Mississippi. 
The copperheads (genus T’rigonocephalus) of America are, if possible, 
more dreaded than even the rattlesnakes, owing to the fact that, with equal 
venom, they are more vindictive and give no warning of their presence. 
The most generally distributed species, T. contortriz, is fond of damp 
meadows, where it is often revealed to the cost of persons engaged in 
mowing or passing through. They not unfrequently get into cellars, 
where they perform an acceptable service in destroying mice and rats. 
The water-moccasin of the Southern States (7. piscivorus) is the pest of 
rice plantations, where negroes are often bitten. This species lives in the 
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