The Poisonous Snares of British Guiana. 29 
recovery from the bite of a rattlesnake unless some such 
certain method of treatment as amputation of the part 
has been resorted to, the reputed cases of recovery from 
the bite of the labarria are as common as the remedies 
employed are inefficacious for the purpose. 
The species of rattlesnake (Crotalus terrificus) which 
is found in the colony, is commonly distributed over 
tropical and sub-tropical America, ranging from Texas 
and New Mexico to Northern Argentine. Specimens 
vary somewhat in tint and markings, at times being very 
dull coloured, and at others quite bright and striking. 
The brown ground colour is usually marked on the neck 
by two black lines which pass into a series of dark 
rhombs with lighter centres along the back, the whole 
being outlined by a series of yellow or paler scales ; 
and the scales are tuberculate and give a very rough 
aspe6l to the skin. Owing to the peculiar markings, 
the skins are in great request for pouches, purses, 
belts, and other such obje6ls — neck-ties even being at 
times prepared from them. 
A peculiar feature in these and the other American 
vipers is the pit situated on each side of the face, below 
and between the nostril and the eye, and which has 
secured for them the distin6live title of ** pit-vipers," 
though its function is by no means evident. 
The most chara6leristic feature of the species is of 
course the rattle, which, as is well-known, is made up of 
a number of separable three-lobed pieces, closely packed 
together and interlocked by the incurving of the first 
lobe of each piece over the second lobe of the preceding, 
which allows the free movement of each with the resulting 
shrill sound. Detailed reference to the stru6lure and de- 
