 There is a complex hermaphroditic reproductive system in pulmonate snails ( those snails that have a lung rather than a gill or gills . ) Their reproductive system is completely internal , except for the active protrusion ( eversion ) of the penis for copulation . The outer opening of the reproductive system is called the " genital pore " ; it is positioned on the right hand side , very close to the head of the animal . This opening is virtually invisible however , unless it is actively in use . 
