There are several varieties of snakes, of which three species (all vipers) are poisonous.
The Elapinae have comparatively short fangs, while those of the vipers, especially the crotaline snakes, are much longer, sometimes nearly an inch in length.
Viperinae, vipers (q.v.) or adders.
About 60 species of pit-vipers are recognizable.
American pit-vipers by the possession of a loreal shield, i.e.
If the venom is slowly absorbed, the blood loses its coagulability, owing to the breaking down of the red blood-corpuscles, most so with vipers, less with Australian snakes, least so with the cobra.