GASTEROPODA. 995 
Fossil, 20 species. Hocene—. Britain and France. Coal- 
strata, Nova Scotia. (Lyell.) 
OC. maxima, Grat., Miocene, Dax, is two inches in length. 
Famity IJ.—LimAcipm. 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. Limazx Sowerbii, Fér. Brit. 
Limax, L. Slug. 
Type i. maximus. Pl. XII., Fig. 25. (L. cinereus, Miller.) 
Shell internal, oblong, flat, or slightly concaye 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 strize ; 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 moye 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 themselvesin 
drought and frost. Limaw noctilucus, Fér, (Phosphorax, Webb), . 
found in Teneriffe, has a luminous pore in the posterior border 
of the mantle. 
