Pit viper

The Crotalinae, commonly known as pit vipers, crotaline snakes, or pit adders, are a subfamily of venomous vipers found in Eurasia and the Americas. These are the only viperids found in the Americas. They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on both sides of the head. For more information, visit the Wikipedia entry. Get back to Snakes
Cottonmouth	Desert horned viper	Eyelash viper
Guatemalan palm viper	Mamushi	Okinawa habu
Rattlesnakes	ruby-eyed green pit viper	Southern copperhead