GASTEKOPODA. 



195 



When the animal is touched it enters very deeply into its 

 shell, at all times is hidden by it, and sometimes even fills 

 the entrance with earth. The New Zealanders fish for, 

 and use it as food. 



Family 7. — CYCLOSTOMA CEA. 



The body of these Mollusca can be drawn entirely into 

 a spiral shell, which has a round, entire aperture ; the 

 head has two tentacula, with eyes placed either on the 

 outer or inner side; they possess an operculum. — Ter- 

 restrial. 



Cyclostoma. Lam. — Shell globose, either flattened 

 or turreted; aperture circular; the margin of both lips 

 united and slightly turned back; 

 closed by a shelly or horny oper- 

 culum. Animal, with a proboscidi- 

 form muzzle ; two subulate ten- 

 tacles, eyes at their external bases ; 

 foot ovate; mantle quite free.* — 

 175 species f; also fossil. 



The shells of this genus vary 

 very much in form ; some being very flat, others having 

 the apex lengthened out, but they all have the aperture 

 round. They are found principally in the Torrid Zone, 

 in the vicinity of lakes and rivers ; but one species, 

 C. elegans, is a native of Britain, and is found in woods 

 amongst moss and stones. The inhabitant, it is said, will 

 survive imprisonment many months, like many other oper- 

 culated Molluscs. Guilding mentions that C. suspensum, 

 a West Indian species, suspends itself from the trees by 

 a few threads. 



* Forbes's British Moll. f Sowerby's Thesaurus, 



o 2 



