GASTEROPODA. 



295 



Fossil, 20 species. Eocene — . Britain and France. Coal- 

 strata, Nova Scotia. (Lyell.) 



C. maxima, Grat., Miocene, Dax, is two inches in length. 



Family II. — Limacid^. Slugs. 



Shell small or rudimentary, usually internal, or partly con- 

 cealed by the mantle, and placed over the respiratory cavity. 



Animal elongated ; body not distinct from the foot ; head and 

 tentacles retractile ; tentacles 4, cylindrical, the upper pair sup- 

 porting eyes ; mantle small, shield-shaped ; respiratory and 

 excretory orifices on the right side. 



Fig. 124. Limax Sowerbii, Fir. Brit. 



LiMAX, L. Slug. 



Type L. maximus. PL XII., Fig. 25. (L. cinereus, Miiller.) 



Shell internal, oblong, flat, or slightly concave beneath, 

 nucleus posterior ; margin membranous ; epidermis distinct. 



Animal, foot pointed and keeled behind; mantle shield- 

 shaped on the front of the back, granulated or marked with 

 concentric striae ; respiratory orifice on the right side, near the 

 posterior margin of the mantle ; reproductive orifice near the 

 base of the right ocular tentacle ; lingual teeth tricuspid, those 

 near the margin simple, aculeate. 



The slugs are connected with the snails by Vitrina; their teeth 

 are similar, but have more elongated cusps. The creeping-disk or 

 sole of the foot, extends the whole length of the animal ; but they 

 frequently lift up their heads like the snails, and move their ten- 

 tacles in search of objects above them. They often climb trees, and 

 some can lower themselves to the ground by a mucous thread. 

 When alarmed they withdraw their heads beneath the mantle, 

 as in Fig. 124. Slugs feed chiefly on decaying vegetable 

 and animal substances ; they oviposit at any time of the spring 

 and summer when the weather is moist, and bury themselves in 

 drought and frost. Limax nodilucus, Fer. (Phosphorax, Webb), 

 found in Teneriff'e, has a luminous pore in the posterior border 

 of the mantle. 



