310 MANUAL OF THE MOLLUSCA 



Helicina, Lamarck. 



Type, H. Neritella, liam. 



Synonyms, Oligyra, Say. Pachytoma, Sw. Ampultina, Bl. 

 Pitonillus, Montfort. 



tShell 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. 



Animallike Cydophorus ; lingual teeth 3.1.3. (Gray.) 



Distribution, 162 species. West Indies, Tropical America, 

 Pacific Islands, Australian Islands, Philippines. 



Suh-genera. Lucidella (aureola). Gray. Peristome more or 

 less toothed internally. 8 species. West Indies, Tropical 

 America. 



TrochatcUa (pulchella), Sw. Shell not callous beneath ; peri- 

 stome simple, expanded. West Indies 20 species, Venezuela 1. 



Alcadia, Gray. A. Brownei, PI. XII., Fig. 43. Jamaica. 

 Shell helix-shaped, often velvety, callous beneath ; columella 

 flattened, straight ; peristome slit in front ; operculum shelly, 

 semi-ovate, with a tooth-like process adapted to the slit in the 

 peristome. JDistribution, 17 species. Cuba, Jamaica, and Hayti. 



Stoastoma, C. B. Adams. 



Etymoloyy, stoa, pillared, stoma, mouth. 



Type, S. pisum. Ad. 



Shell minute, globose-conic or depressed, spirally striated; 

 aperture semi-oval ; peristome continuous ; inner margin 

 straight, forming a small spiral keel round the umbilicus; 

 operculum shelly, lamellar. 



Distribution, 19 species. Jamaica. 'S'. succineum (Electrina, 

 Gray) has smooth whorls. I. Opara, Polynesia. 60 new species 

 have been added by the Hon. E. Chitty, who divides them 

 among several new genera. 



Family VIL— AcicuLiDiE. 



Shdl elongated, cylindrical ; operculum thin, sub-spiral. 



Animal 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. 

 Type, A. fusca, PI. XII. , Fig. 44. 



