i 9 o THE POPULAR SCIENCE MONTHLY. 



tropics, once related to me an experience of his in the West 

 Indies, that throws light upon another phase of snail life, and re- 

 minds one of precisely similar incidents among the Lepidoptera. 

 This naturalist had a habit of holding small snails in his mouth 

 when collecting upon cliffs or trees where climbing was difficult. 

 The light or dull colored species of CylindrelJa, Helicina, etc., 

 caused him no inconvenience, but the snails with conspicuously 

 bright and shining shells, such as occur in the groups Streptostyla 

 and Varicella, were so intensely bitter that he soon learned to let 

 them remain unless he could carry them elsewhere. It is reason- 

 able to conclude that birds find them equally unpalatable. The 

 facts, as far as they are known, seem to indicate that this is an ex- 

 ample of "warning coloration/' such as many conspicuous but 

 nauseous butterflies possess. 



It may be remarked that the custom of holding specimens be- 

 tween the lips is not so rare with field naturalists as fastidious 

 persons might suppose. I confess to having once swallowed a 

 small and very rare specimen while so holding it for a moment. 

 The creature was, alas ! not my own property, and its outraged 

 owner has not yet forgiven me. 



A protective device totally different in kind from those just 

 described has been observed in certain slug-like snails, which 

 have the ability to amputate their own tails, just as a lizard does 

 when seized by that appendage. Dr. Carl Semper has noticed 

 this peculiarity in snails of the genus Helicarion, in the Philippine 

 Islands ; and a species of the genus Prophysaon, of California, has 



lately been seen to lose its tail in 

 the same manner.* 



It is probable that the explana- 

 tion is the same in the case of both 

 lizards and snails — viz., the tail is 

 likely to be the part seized by an 

 enemy just as the escaping creature 

 is disappearing into a sheltering 

 crevice. The advantage of saving 

 the head, even at the expense of the 



Fig. 4.— An Indian Snail, Atopa tail, is obvious. 



achatina. Broken, to show the -r, , ,. -, j ■ 



internal folds. Protective coloring and protec- 



tive resemblance are, however, a de- 

 fense only against the larger enemies of the mollusk, which hunt 

 their game in the open, such as birds, field-mice, and incidentally, 

 conchologists. But, besides these, snails have smaller foes which 

 meet them upon their own ground. The omnipresent Insecta are 



* See article by W. J. Raymond, Why does Prophysaon shed its Tail ? The Nautilus, 

 May, 1890. 



