A hemipenis (plural hemipenes) is one of a pair of intromittent organs of male squamata (snakes, lizards and amphisbaenia). Hemipenes are usually held inverted, within the body, and are everted for reproduction via erectile tissue like that in the human penis. Only one is used at a time, and some evidence indicates males alternate use between copulations. The hemipenis itself has a variety of shapes, depending upon species. Often the hemipenis bears spines or hooks, in order to anchor the male w… (More on Hemipenis)