the vicinity of this piece of woodland, and toward evening, having 

 filled our boxes and bottles with specimens, we turned our footsteps 

 toward the cars. As we reached the edge of the forest, we saw a par- 

 ticularly large log lying in a damp ravine, and we could not resist 

 the temptation to turn it over and see if something new could not be 

 found. Sure enough, there were several specimens of the solitary snail, 



Pyramidula solitaria. One of them 

 was crawling over the damp leaves. 



Underneath another part of the 

 log Howard discovered a whole col- 

 ony of snails, the shells of which 

 were about three-fourths of an inch 

 in diameter, and marked by many 

 ^ Pyramidula "^''^ reddish streaks on a horn - colored 



background. Several of the animals 

 were crawling about, their method of locomotion being slow and care- 

 ful. " This species," said Professor Parker, " is called Pyramidula alter, 

 nata, and is our most abundant species. Unlike most of our Helices, 

 it is gregarious, being generally found in colonies of from twenty to one 

 hundred or more. The animal is sluggish in its movements, but is not 

 at all shy, allowing itself to be picked up and examined without with- 

 drawing into its shell. The shell is very variable in the height of its 

 spire, some specimens having an elevated, convex spire, while others 

 are perfectly flat. This variation is in a great measure due to the 

 habit of crowding itself into narrow crevices, which causes the shell 

 to assume a flat-whorled aspect. The convex forms are generally found 

 in wide, open crevices, or under logs, while the flat-whorled forms are 

 found in small, narrow crevices or under loose bark." 



On the same log with this snail w r ere several others in which the 

 aperture was covered with a glistening film resembling parchment. 

 George asked what this was, and Professor Parker proceeded to enlighten 

 us. " This," he said, " is called an epiphragm, and with this the snail 

 closes the aperture of the shell on the approach of winter. It is formed 

 in the following manner: The animal withdraws into its shell, and 

 places the parts of the body called the collar on a level with the aper- 

 ture, and covers the latter with a quantity of mucus. A little bubble 

 of air is now liberated from the lung, which detaches the film of mucus 

 and makes it project in a convex form from the aperture. At the 

 same moment the animal retreats farther into its shell, and leaves 

 a vacuum between itself and the film of mucus. As the pressure of air 

 is now greater on the outside, the film is pushed in and assumes 



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