their Food and Digestive Organs. 73 



table matter is consumed by them, although many of the 

 snails and slugs are found under putrid leaves and decayed 

 wood. In those places there is shelter from the sun, toge- 

 ther with dampness ; so that it is difficult to determine whe- 

 ther they sojourn in an agreeable dwelling or a well-stored 

 larder." (Edin. Encyc, xiv. 602.) On occasions they eat 

 voraciously ; but, when necessary, they can sustain a fast 

 longer, perhaps, than any other animated beings; snails 

 having been kept for upwards of a year, nay for years 

 [VII. 114.], and the Lymnei and Planorbes for many 

 months, without any food except that small and tenuous por- 

 tion which they might extract from the air or water. (Mutter, 

 Verm., ii. xii.) 



I am not aware that any carnivorous mollusc ever resorts, 

 for variety's sake, to a vegetable diet ; whereas many herbivo- 

 rous ones seem to have a strange hankering after flesh, and 

 become very cannibals in satisfying this propensity. Lister 

 asserts that snails will eat not only bread and cheese, but 

 flesh of all kinds, particularly fish and salted meat (Exer. Anat. 

 de Cochleis, p. 90.) ; and, in another place, he tells us that, 

 having once placed an individual of the Helix aspersa with 

 another of the iimax ater in a vessel together, he found, on 

 the following day, that the former had slain the slug, and had 

 miserably torn and eaten its skin, " tantus animus est etiam 

 pigerrimis animalibus." (Anim. Ang., p. 114.) I have re- 

 peatedly seen the black slug (Z,imax ater) feeding on in- 

 dividuals of its own species which had been accidentally 

 crushed, and were yet scarcely dead ; and the observations of 

 Mr. Power, which have been since confirmed, show that they 

 feed voluntarily on earthworms, dead or dying. Of the 

 aquatic tribes, we are informed by Mr. Jeffreys, that " the 

 food of the Limnei is animal and vegetable matter in different 

 states of putridity ; which makes them deserve the perhaps not 

 unapt epithet of ' scavengers of the waters.' In the absence of 

 other nourishment, they will even devour each other, piercing 

 the shell near its apex, and eating away the upper folds of its 

 inhabitant. This accounts for the mutilated and often im- 

 perfectly repaired state of the upper volutions of some spe- 

 cimens." (Lin. Trans., xvi. 371.) 



The mouth in this tribe, as in other Mollusca, is always 

 anterior and terminal, with, often, an inferior aspect; in 

 Doris, and Cyclostoma, and a few others, it is prolonged 

 into a sort of snout, which can be shortened or elongated to 

 a small extent; in Aplysia and Pleurobranchus [VII. 348.], 

 there are labial tentacula at the sides ; and it is overshadowed 

 in the Tritonia by a deeply crenate veil, which receives a 



