ACHATINA.— ONCHTDIUM. 



41 



to lodge the entire animal {jig. 26) : the shell 

 is thin and translucent, and obtains its name 

 from a supposed resemblance to amber: they 

 live upon plants that grow along the margins 

 of rivulets and brooks. 

 19. The genus of 



ACHATINA {jig. 



27) is composed of 

 Fi^. 26. large snails, which, 

 AMBRETTE. in Warm countries, 

 feed on shrubs ; they have an oblong 

 shell with the opening wider than it 

 is high, without a thickened lip, and 

 truncate at the extremity of the colu- 

 mella, a disposition somewhat analo- 

 gous to that of the shell of most ma- 

 rine gasteropods. 



20. The family of Pulmonea 

 AauATiCA have but two tentacles 

 {jig. 18, page 33) ; their mode of 

 respiration obliges them to come fre- 

 quently to the surface of the water to 

 breathe : they cannot keep at great 

 depths, and they ordinarily live in 

 fresh waters, or near coasts. 



21. As in the preceding family, we find here mollusks without 

 a shell, and others that are provided with one : the first form tho 

 genus of Onchidiinn {fig. 28), which have a very straight and 

 very extensible elongated body ; they inhabit the fresh waters of 



Fig. 27. ACHATINA. 



Fig. 28. ONCHTOICJM L.EVE. 



19. What shells form the genus of Achatina? (pronounced a-Jca-te-va), 



20. What are the characters of the family of Pulmonea Aquatica. 



21. What are the characters of the genus Onchidium ? 



4* w^....,,.,W,:. 



