Family Viperidae

Agkistrodon - Members of this genus have a number of features in common.

Atropoides - All of these snakes are extremely thick-bodied, with A.

Bitis - Size variation within this genus is extreme, ranging from the very small B.

Bothriechis - Species that belong to this genus typically reach lengths of 60-80 cm, while B.

Bothrops - These snakes range from small, never growing to more than 50-70 cm, to large at over 200 cm in length.

Cerrophidion - These snakes grow to a maximum length of 82.

Crotalus - Members of this genus range in size from only 50-60 cm , to over 150 cm .

Daboia - This snake grows to a maximum length of 166 cm .

Macrovipera - Except for M.

Vipera - Members are usually small and more or less stoutly built.

Ophryacus - The larger of the two species, O.

Porthidium - This is a groups of group of small species, adults ranging in size from 55 cm to 75 cm in length .

Protobothrops - Most are relatively small, primarily arboreal species, with thin bodies and prehensile tails.

Sistrurus - Sistrurus species differ from the larger rattlesnakes of the genus Crotalus in a number of ways.

Parias - The earliest evidence of parias pertains to eastern Spain, to the County of Barcelona and the Kingdom of Aragon, which exacted a very early one—called the vetus paria or "old paria"—from the taifa of Zaragoza.

Zhaoermia - Known only from the type locality: "Pingkeng, Mangshan , Izhang County, Hunan Province, China.