The Poisonous Snakes of British Guiana. 2^ 
Such are the vipers and those members of the Colubrine 
division which h^diV anterior, grooved, or perforated fangs 
in conne6lion with the poison glands. The members of a 
very large se6lion of what are commonly termed harmless 
snakes, are however really poisonous to a certain extent, 
possessing grooved posterior fangs, the bite from which 
is capable of paralyzing or killing the small prey on 
which they teed. On man this bite produces, at any 
rate in certain cases, an effe6l quite independent of the 
mechanical injury. This the writer personally experi- 
enced in the case of the common species of Erythrolam- 
prus (E, 3SSculapii=^E. venustissinms) ^ as recorded in 
Timehriy Vol. vi., New Series (1892), p. 174. Three 
bites from the snake were received on the first finger, the 
posterior fangs being driven down deeply into the flesh 
each time, and after a short interval very considerable 
swelling and severe pain resulted, which was only relieved 
after about four hours, though the place was tender for a 
much longer time. 
A similar effect on man is certainly produced by the 
bite of some Colubrine snakes which are destitute of 
grooved teeth. This has been dire6lly noted by the writer 
in the case of two species with enlarged, elongated pos- 
terior teeth, namely Xenodon sever us and Helicops angu- 
latusj where the teeth were driven deeply down into the 
flesh, and it would appear that ill effe6l is only caused by 
a large wound of a great degree of penetration admitting 
matter from the buccal glands, which would be impossible 
in a bite of slight or only moderate depth. An interesting 
relation between the two groups is seen in forms of the 
common species of Erythrolamprus, in which certain speci- 
mens are destitute of the groove on the posterior fangs, 
