310 TRUNCATELLIDiE. 



In this division, which comprises, at present, hut a single 

 family, the meuihers inhahit the margins of the sea, damp 

 woods, the hanks of rivers, and Mangrove swamps. Although 

 a humid atmosphere, and even, in some cases, the spray of 

 the sea seems essential to their welfare, yet they appear to 

 he truly pulmoniferous. 



Fam. TRUNCATELLID.E. 



Animal with a broad, produced, hilohed muzzle; ten- 

 tacles flattened, sub-triangular ; eyes sessile on the middle 

 of their upper bases. Foot very short and rounded. 



Operculum horny, sub-spiral. 



These animals progress by means of their foot and the 

 fore part of the muzzle, fixing one as a point of support, 

 and drawing the other after it. Gray calls them, in conse- 

 quence, "Looping Snails." 



Genus TRUNCATELLA, Risso. 



Operculum sub-membranaceous, obsoletely spiral. 



Shell, in the young, subulately turreted, in the adult, cy- 

 lindrical and truncated ; aperture oblong-oval ; peristome 

 simple or double, margins rather wide apart, united by a 

 callus. 



Syn. Choristoma, Crist, and Jan. Fidelis, Risso (young). 



Ex. T. truncatula, Montagu, pi. 88, fig. 1. Operculum, 

 T. truncatula, fig. 1, a. Shell, T. truncatula, fig. 1, b. 



The species of this genus inhabit the East and West 

 Indies, Britain, the Mediterranean, and the Islands of the 

 Corean Archipelago. The animals are amphibious in their 

 habits, being sometimes found under heaps of sea- weed on 





