14 MANUAL OF THE MOLLUSCA. 



had been more than a year out of water.* The pond-snails 

 {ampuUarice) have been found alive in logs of mahogany from 

 Honduras (Mr. Pickering) ; and M. Caillaud carried some from 

 Egypt to Paris packed in saw-dust. Indeed, it is not easy to 

 ascertain the limit of their endurance ; for Mr. Laidlay having 

 placed a number in a di'awer for this purpose, found them alive 

 after ^w years, although in the warm climate of Calcutta. The 

 cydostomas, which are also operculated, 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 huUmi, 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 

 papilio and tectiformis) survived a fast and imprisonment in 

 j^ill-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. 



But the most interesting example of resuscitation occurred to 

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

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

 Museum on the 25th of March, 1846 ; and on the 7th of March, 

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

 in the interval (as the paper had been discoloured, 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 marvellous 

 recovery. Advantage was taken of this cii'cumstance for making 

 a sketch of the living animal (Fig. 2). 



The permanency of the shell-bearing races is effectually pro- 

 vided for by their extreme fecundity ; and though exposed to a 

 hundred dangers in their early life enough survive to re-people 

 the land and sea abundantly. The spawn of a single doris may 

 contain 600,000 eggs (Darwin) ; a river-mussGl has been esti- 

 mated to produce 300,000 young in one season, and the oyster 

 cannot be much less prolific. The land-snails have fewer enemies, 

 and lay fewer eggs. 



* " It was alive 498 days after it was taken from the pond ; and in the interim 

 had Deen only twice for a few hours in water, to see if it was alive." — Mev. W. O, 

 Neivnham. t Ann, Nat. Hist. 1850, 



