234 HELIX. 



known ground (the board had lain in the same place for several 

 days). I watched its movements by a lamp set far off so as to give 

 only a faint light ; but when it reached the pot the animal became 

 shaded by weeds which grew there, and I found it necessary to 

 bring the lamp near in order to observe the movements of the 

 snail's lips and tentacles. It climbed the pot rapidly, mending its 

 pace as it got nearer; then it examined the rim with care, and at 

 last crawled over the mould. For a quarter of an hour it wandered 

 among the w r eeds - in the pot licking them frequently. When I saw 

 it explore the soil with its lips and larger tentacles, while the re- 

 productive orifice seemed to open from time to time, I thought that 

 it was seeking a convenient spot to lay its eggs. At last it came up 

 to the banana, mounted it, and began to gnaw the leaf previously 

 attacked, exactly where it had left off before. I was standing a 

 little way off to avoid disturbing the snail, but could readily detect 

 the peculiar odor of the gnawed leaf. Very likely the snail could 

 perceive, even in an uninjured leaf, that scent which only became 

 apparent to me when the leaf was bruised or cut, and this may 

 have helped to guide its course. Scent alone, will not, however, ex- 

 plain all the movements of the animal. At. 2 p. M. I left it feeding. 



"June 11. At 10 A. M. very little of the leaf had been devoured. 

 The snail was comfortably established, as before, between the col- 

 umn and the pot. 



"After this I noticed the snail wandering over a vine which trailed 

 about the column and upper veranda. Finding that it was disposed 

 to escape to the next garden, I opened it on June 17th, to see whether 

 it was ready to lay eggs. There was not a single egg in the oviduct. 



"These observations seems to show that a land-snail may possess 

 an instinct which enables it to choose its abode and return to it at 

 pleasure. We have here the same love of home and topograph- 

 ical knowledge which have been observed, and noted with wonder, 

 in the limpet." 



V 



Three subsections may be distinguished : 



POM ATI A, s. sir., of which Helix pomatia may be taken as the type. 



CRYPTOMPHALUS Moq.-Tand., 1855. Imperforate; last whorl de- 

 scending at aperture ; peristome in every part expanded. Type H. 

 aspersa. 



CAXTAREUS Risso, 1826. Imperforate, thin, globular, the spire 

 short, aperture large, peristome and columellar arcuate, thin, sim- 

 ple. Luce-no, Hartm., Tapada Gray and Cantha re us Agassi z are 

 synonyms. 



Pomatia and Cantaretts have calcareous, and Oryptomphalw mem- 

 branous epiphragm. 



