 In "advanced" (Caenophidian) snakes, the broad belly scales and rows of dorsal scales correspond to the vertebrae, allowing scientists to count the vertebrae without dissection.At the end of the ventral scales of the snake is an anal plate that protects the opening to the cloaca (a shared opening for waste and reproductive material to pass) on the underside near the tail.This anal scale may be single or divided into a pair.