3810 MANUAL OF THE MOLLUSCA 
HELICcINA, Lamarck. 
Type, H. Neritella, Lam. 
. Synonyms, Oligyra, Say. Pachytoma, Sw. Ampultina, BL 
Pitonillus, Montfort. 
Shell globose, depressed or keeled, callous beneath; aperture 
squarish or semi-lunar; columella flattened; peristome simple, 
expanded ; operculum shelly or membranous, squarish or semi- 
ovate, lamellar. 
Animal like Cyclophorus ; lingual teeth 3.1.3. (Gray.) 
Distribution, 162 species. West Indies, Tropical America, 
Pacific Islands, Australian Islands, Philippines. 
Sub-genera. Lucidella (aureola), Gray. Peristome more or 
less toothed internally. 8 species. West Indies, Tropical 
America. : 
Trochatella (pulchella), Sw. Shell not callous beneath; peri- 
stome simple, expanded. West Indies 20 species, Venezuela 1. 
Alcadia, Gray. A. Brownei, Pl. XII., Fig. 48. Jamaica. 
Shell helix-shaped, often velvety, callous beneath; columella 
flattened, straight; peristome sht in front; operculum shelly, 
semi-ovate, with a tooth-hke process adapted to the slit in the 
peristome. Distribution, 17 species. Cuba, Jamaica, and Hayti. 
SToasToMA, C. B. Adams. 
Etymology, stoa, pillared, stoma, mouth. 
Type, 8. pisum, Ad. 
Shell minute, globose-conic or depressed, spirally striated ; 
aperture semi-oyal; peristome continuous; inner margin 
straight, forming a small spiral keel round the umbilicus; 
operculum shelly, lamellar. 
_ Distribution, 19 species. Jamaica. SS. succinewm (Electrina, 
Gray) has smooth whorls. I. Opara, Polynesia. 60 new species 
have been added by the Hon. EH. Chitty, who divides them 
among seyeral new genera. 
Famity VII.—AcicuLipa. 
Shell elongated, cylindrical; operculum thin, sub-spiral. 
Arximal with the muzzle rather produced, slender and trun- 
cated; eyes sessile on the upper part of the head, behind the 
base of the slender tentacles; foot oblong, short, pointed 
behind. 
AcicuLA, Hartmann. 
‘ype, A. fusca, Pl. XII., Fig. 44, 
