(. \MKorODA. 



151 



phorescent. Like the Snails, they are fond of damp localities, and 

 at times become great pests to fanners in devouring the young 

 shoots of the growing com. Testacella, which is found in this 

 country, differs from the Slugs in having an external shell at the 

 tail-end of the foot. It is not slimy, and lives under ground, 

 feeding upon earthworms. 



The first group of the aquatic air-breathers, the Auriculida, [Case 

 chiefly inhabit salt or brackish water. The largest forms are l'A.j 

 tropical and found at the mouths of rivers, among the routs and 

 stems of mangrove-trees, or in damp woods near the sea. 



The Limmeidce are only found in fresh water. Most of them < ;; 

 occasionally rise to the surface to breathe, where they glide aloug 17,b-d.] 

 foot uppermost, at times suspending themselves by a glutinous 

 thread, after the fashion of a spider. All countries appear to have 

 their peculiar species. 



Fig. 20. 



\& '/ 

 British Pond-Snail {Limneea stagnalis). 



1. Upper view : a, foot ; b, tentacles ; c, eye ; d, muzzle. 



2. Lower view : letters a, b, c as above ; e, mouth ; /, respiratory orifice. 



The freshwater Limpets (Ancylus) live attached to stones and r,-,,, 

 leaves of plants, and have not the habit of floating, but, like the 17 »•] 



