SLUGS. SNAILS. 



14. Some, called ARIONS, have the pulmonary orifice situate 

 near the anterior part of the dorsal shield, such as the Limax 

 rufus, which is everywhere met with in wet weather; [a de- 

 coction of this species is sometimes used in France for pulmo- 

 nary disorders :] the others, named Limax properly so called, or 



m ro 



4h 



-. st 



Fig. 22. LIMAX RUFUS. 



Lima, have this orifice situate more posteriorly, and frequently 

 have a pretty well formed internal shell ; the Limax cinereus, 

 wm'ch inhabits caves and shady forests, belongs to this division, 

 as well as the Limax agrestis, which abounds in some countries, 

 and is very injurious to agriculture. 



We give the names of VAGINULA, TESTACELLA, and PARMA- 

 CELLA to other naked gasteropods, nearly resembling the limaces, 

 but which differ from them in the position of the anus, the extent 

 of the mantle, &c. 



15. The SNAILS Helix form the most important tribe of 

 terrestrial pulmonea with a complete and apparent shell. 

 Their organization differs very little from that of the limaces ; 

 the mantle, instead of being in the form of a convex shield, 

 constitutes a large cone twisted on itself, containing the viscera, 

 which is covered by the shell (fig- 21, p. 35). We distinguish 

 them by their shell, the opening of which is ordinarily raised 

 like a pad or collar, forming a thickened lip in the adult ; the shell 

 is a little twisted by the projection of the penultimate whorl of 

 the spire, and in this way takes somewhat of a crescent shape. 

 In snails properly so called, this opening is at least as broad 

 as high, and the shell is sometimes globular and sometimes 

 depressed. The habits of these mollusks are nearly the same 

 as those of the limaces. In summer they are very voracious, 

 but in the autumn they eat very little, and, on tbe approach of 



Explanation of Fig. 22. Limax rufus : st. the eyes on the extremity 

 of the superior tentacles ; m. the mantle ; ro. the notch over the pulmona- 

 ry cavity. 



14. What are Arions ? 



15. What are the general characters of snails ? What are their habits ? 

 Do their wounds heal ? In what respect does the genus Heiu differ from 

 the genus Limax ? 



