As a criterion to determine whether or not snails were hibernating, the presence or absence of an epiphragm or other aperture plug was used. If an aperture stopper was present it was concluded that hibernation was taking place; the absence of such a stopper was considered evidence that the animals were not in hibernation. Concerning the preparation for extended winter hibernation Baker (1902) states, "In October or November the snail ceases to become active and prepares to hibernate. This it does by secreting a membrane and placing it over the aperture." Binney (1885) describes epiphragm formation, referring to North American land snails in general as follows, "The animal being withdrawn into the shell, the collar is brought to the level with the aperture, and a quantity of mucus is poured out from it and covers it. A small quantity of air is then emitted from the respiratory foramen, which detaches the mucus from the surface of the collar, and projects it in a convex form, like a bubble. At the same moment, the animal retreats farther into the