inhabiting the United States 



479 



/ 



the time with precision, it consists of one whorl and a 

 halfj the length of the column or axis being about one 

 eighth of an inch, and the breadth somewhat less. No 

 umbilicus is then discernible. I have not been able to 

 determine how much time is required to complete its 

 growth, hut I am induced to believe, that the reflected 

 lip, the evidence of maturity, is added in the second or 



third 



year 



In the month of October, or at the epoch of the first 

 frost, the snail ceases to feed, fixes itself to the under 

 surface of the substance by which it is sheltered, with the 

 aperture of the shell upwards^ and disposes itself for its 

 annual sleep, or hybernation. Withdrawing within the 

 shell, it forms a membranous covering, or epiphragm, 

 over the aperture, and as the weather becomes colder 

 retires further, forming membrane after membrane with 

 only a small interval between them, until sometimes there 

 are as many as six of these divisions. The circulation 

 becomes slower, the pulsations of the heart, which in the 

 season of activity vary from forty to sixty in a minute 

 according to the temperature of the air, decrease in fre- 

 quency and strength, until finally they are imperceptible. 

 The other functions of the body cease, and a state of 

 torpidity succeeds, which is only interrupted by the re- 

 viving heat of the next spring's sun. 



During the months 



May 



nous partition, and comes forth to participate in the 



warmth 



At first it is weak 



and inactive, but recovering in a short time its appetite, 

 ■it commences feeding, and resumes Its former activity. 



This species, as before remarked, offers but few varie- 

 ties when arrived at maturity ; but the young shell might 

 be mistaken for a distinct species, it being umbilicated. 



