Pituophis
Pituophis is a genus of nonvenomous colubrid snakes commonly referred to as gopher snakes, pine snakes, and bullsnakes, which are endemic to North America. Geographic range. Species and subspecies within the genus "Pituophis" are found throughout Mexico, the Southern and Western United States and Western Canada. Description. All species of "Pituophis" are large and powerfully built. The head is relatively small in proportion to the body and it is only slightly distinct from the neck. The rostral is enlarged and elongated, imparting a characteristic somewhat pointed shape to the head. All the species occurring in the United States have  four prefrontals instead of the usual two. Modified epiglottis. In all snakes of the genus "Pituophis", the epiglottis is peculiarly modified so that it is thin, erect and flexible. When a stream of air is forced from the trachea, the epiglottis vibrates, thereby producing the peculiarly loud, hoarse hissing for which bullsnakes, gopher snakes and pine snakes are well known.