86 SYSTEMATIC ARRANGEMENT 



Teeth large, brown, 3 • 1 • 3 ; outer lateral slender, linear, thin, nearly 

 straight, curved at the tip. 



c. Shell with very close long spiral epidermal fringes. Schasi- 

 cheila, Shutt. 



10. H. alata. 



5. Alcadia. 



Operculum annular, rather solid, semiovate, furnished at its lower 

 extremity with a tooth-like appendage. Shell heliciform, turbinate, 

 subglobose or slightly depressed, for the most part hairy, covered 

 with callus round the columella, which is flattened, nearly rectilinear. 

 Periostraca often covered with lines of hairs. Aperture semiovate, 

 rather triangular. Peristome more or less expanded, separated from 

 the columella by a distinct, for the most part curved, slit. 



1. A. major. 



Fam. VIII. PROSERPINIDiE. 



"Tentacles two, subulate. Eyes subsessile, on the outer side ol 

 their base." — Shuttleworth, 1854. Mantle more or less expanded 

 over the shell ? Shell spiral, depressed, polished ; whorls rounded ; 

 spire low. Mouth lunate, cavity with spiral laminae on the inner 

 and outer lip. Peristome acute ; axis covered with a callous deposit. 

 Operculum none. — Bland. 



Terrestrial. Mexico ; Jamaica and Cuba. 



The animal, as in Stoastoma, Helicina, Neritina, Auricula, and 

 some Helicidce, absorbs the septa between the upper whorls of the 

 spire. — Bland. 



1. Proserpina. 



Character of Family. 

 1. P. nitida. 



b. Pseudopneumona. Gills in very numerous cross folds on tht 

 inner surface of the mantle. Eyes on the front side of tht 

 base of the tentacles. Operculum spiral (p. 78). 



Fam. IX. LITTORINID^E. 



Shell spiral, free. Mouth of the shell entire. Mantle edg< 

 simple. Foot moderate : for walking. Trunk produced, wrinkled 

 not retractile. Jaws horny, distinct. Tentacula far apart on sid( 

 of head. Gills : one, very large, occupying nearly the whole surfacf 

 of the cavity, and formed of numerous flat free plates. Teeth few 

 central 1 ; lateral 3 ; 3, converging. The opercular lobe is simple 

 not appendaged behind. 



Marine. Amphibious. 



