SLUGS. 



are longest, have the eyes at their extremities. The mouth is 

 armed with one palatine tooth, and a small tongue studded with 

 microscopic teeth ; and the body varies in form ; some are 

 naked or only provided with an internal shell, while others have 

 an external shell spirally twisted, with a blunt summit, and the 

 mouth without a notch. The small tribe formed by the first is 

 divided into Limax, Vaginula, &c. The tribe of terrestrial pul- 

 monea with an external shell comprisesthe genera o^ helix, vitrina, 

 bulimus, pupa, cho?idrus, succinea, clausilia, and achatina, 



12. The LiMACEs (slugs) form the type of the terrestrial 

 pulmonea without apparent shell. The body, as every one 

 knows, is elongated, and their mantle is a fleshy disk, scarcely 

 separated from the rest of the skin {fig. 22, m,) and' which only 

 occupies the fore part of the back, where it covers the pulmo- 

 nary cavity ; it often encloses in its thickness a small, flat shell. 

 On the right side of this species of shield, there is a notch, at 

 the bottom of which we observe a contractile opening {fig. 22, 

 ro), that leads into the pulmonary cavity ; the anus is situate 

 upon the anterior border of this respiratory orifice, and a third 

 opening belonging to the procreative apparatus is situate on the 

 external side of the base of the right superior tentacle. The 

 four tentacula are cylindrical, more or less swelled at the end, 

 and hollow ; they are drawn in and pushed out, on unrolling 

 themselves, like the inverted fingers of a glove, by the aid of 

 muscular fibres lodged in their interior; the eyes, which are 

 borne on the ends of the superior tentacles {fig. 22, si), are 

 .black; the mouth is armed with a sort of palatine tooth in the 

 form of a crescent, and a smooth tongue. The heart is lodged 

 in a particular cavity beneath the mantle, and is composed of an 

 oval auricle, which receives a large pulmonary vein, and a pear- 

 shaped ventricle, from which the aorta arises. And there exists 

 near the heart a secretory apparatus which pours out a viscid 

 matter upon the external surface, through an excretory canal, 

 opening near the respiratory orifice. 



13. These animals are herbivorous: they feed principally 

 upon young plants, fruits, mushrooms, and are most voracious 

 towards evening. During the heat of the day they remain con- 

 cealed in holes under stones, or some heap of half-decayed 

 leaves, or even in the earth, and they seldom go out except in 

 the morning and evening, when the air is humid; they are 

 especially abundant after rain. During the cold season they 

 bury themselves in the ground and remain torpid. 



12. What are the general characters of the Lima'ces ? 



13. Upon what do the Lima'ces feed? Where are they found? What 

 Decomes of them in the cold season ? 



