HABITS AND ECONOMY OF THE MOLLUSCA. 14t 



opereulated, are well known to survive imprisonments of many 

 months ; but in the ordinary land-snails such cases are more 

 remarkable. Some of the large tropical Bulimi, brought by 

 Lieutenant Graves from Valparaiso, revived after being packed, 

 some for thirteen, others for twenty months. In 1849, Mr. 

 Pickering received from Mr. Wollaston a basket-full of Madeira 

 snails (of twenty or thirty different species), three-fourths of 

 which proved to be alive after several months' confinement, 

 including a sea voyage. Mr. Wollaston has himself told us that 

 specimens of two Madeira snails {Helix pa'pilio and tectiformis) 

 survived a fast and imprisonment in pill-boxes of two years and 

 a half, and that a large number of the small Helix turricula, 

 brought to England at the same time, were all living after having 

 been enclosed in a dry bag for a year and a half. 



Mr. Crosse has kept alive without nourishment, for more 

 than two years, several specimens of Helix signata of Rome ; 

 and R. E. C. Stearns mentions a Helix Veatchii from Cerros 

 Island, Lower California, which passed six years, from 1859 to 

 1865, without food. 



This relaxation of the principal vital functions, will even, in 

 certain cases influence reproduction. Gaskoin cites the case of 

 a Helix lactea, obtained of a Mogador merchant in April, 1849, 

 which had been kept for two years in a drawer, exposed to a 

 dry atmosphere and dust. This isolated Helix laid thirty eggs 

 in October, 1849, which attained their full size in less than a 

 year. It could be objected to the opinion of Gaskoin, who 

 considered this fact as proving an arrest of gestation, that 

 parthenogenesis or fecundation in ,situ^ is possible in the Helices, 

 the genital gland including both male and female elements. 



But the most interesting example of resuscitation occurred 

 to a specimen of the Desert-snail, from Egypt, chronicled by Dr. 

 Baird. This individual was fixed to a tablet in the British 

 Museum on the 25th of March, 1846 ; and on the tth of March, 

 1850, it was observed that he must have come out of his shell 

 in the interval (as the paper had been discolored, apparently in 

 his attempt to get away) ; but finding escape impossible, had 

 again retired, closing his aperture with the usual glistening- 

 film ; this led to his immersion in tepid water and marvelous 

 recoverj'^. 



The small effect which extremes of teraperatiire has upon 

 mollusks assures their conservation. Anodontas and Paludinas 

 survive freezing, and will reproduce after being thawed (Joly). 

 Unio Requieni lives in the thermal waters of Barbotan (France), 

 the temperature of which is 86 degrees, in company with Limnsea 

 jDeregra and Physa acuta. Analogous cases are recorded. Near 

 Bona, Algeria, a Hydrobia lives in a thermal spring, the temper- 

 ature of which is 108 degrees. Planorbis Oregonensis, Trj^on, 



