What is "heterodon"

Heterodon is a genus of harmless colubrid snakes endemic to North America. They are stout with upturned snouts and are perhaps best known for their characteristic threat displays. Three species are currently recognized. Members of the genus are commonly known as hog-nosed snakes, North American hog-nosed snakes, and sometimes puff adders (though they should not be confused with the venomous African vipers of the genus Bitis).