77 



Sect. 2. Edriophthahnn. 



Eyes sessile, or on very short tubercles on the outer side of the 

 base of the tentacula. Male organ on right side of nape. 



a. Shell free, spiral. Operculum annular. Teeth few, unequal, 

 1 central and 3 lateral on each side, converging. Male or- 

 gan at base of right tentacle, Lister, Cuvier. Gills three 

 ranges of filaments. Fluviatile. 



Fam. 11. ViviparidcB. 



1. Viviparus, n. 251=Viviparella, Rafin. Operculum horny, 



nucleus near the middle of inner side. 



1. V. vulgaris. Helix viviparus, Midler, t. 124. f. 3? ; Cuvier, t.124. 



f. 6. Nerita viviparus, Sturm, 1. 124. f. 9. 



2. V. bengalensis, Hardwicke, 1. 124. f. 2. India. 



3. V. ampullariformis. Paludina a., Eydoux, t. 127 «• f- 5. 



4. V. decisa, Haldm. t. 310. f. 10. 



2. Paludomus, n. 252=Tanalia, n. 219, is only a subdivision. 



Operculum horny, nucleus near the front of outer side. 



1. P. conicus, Gray, P. Z. S. 1849. 



2. P.? Paludine boueuse, Eydoux, t. 127 a. f> 4, edge of mantle 



festooned. 



3. Bithinia, n. 253. Operculum with a shelly internal coat, 



nucleus subcentral. 



1. B. tentaculata. Cyclostoma impura, Sturm, 1. 124. f. 8; Chiaje, 



t. . f. . 



2. B. viridis. Cyclostoma v., Sturm, t. 124. f. 7 • 



4. Nematura, n. 207. Operculum annular, ovate, thick, shelly ; 

 nucleus subcentral; shell mouth contracted. 1. N, Delta?. 

 2. N. polita. 



B. Shell spiral, free. Gill inclosed, in one or three lines on left 

 side of mantle-cavity. Operculum spiral. Teeth few, cen- 

 tral 1, lateral 3 - 3, converging. 



Fam. 12. Littorinidce. 



Foot moderate, for walking ; trunk produced, wrinkled, not re- 

 tractile ; tentacula far apart on side of head ; gills 2, one very 

 large, occupying nearly the whole surface of the cavity and formed 

 of flat free plates. Amphibious. 



a. Operculum ovate, few whorls. 



1. Assiminea, n. 193. Eyes on pedicels, united to the short 



tentacles. 

 1. A. Grayi, Berkeley, 1. 123. f. G; Gray, t. 51. f. 8. 



2. Littorina, n. 194. Eyes sessile. 



1. L. littorea. Turbo 1., Cuvier, t. 51. f. 4. 



2. L. varia. Lit. variee, Eydoux, t. 127 «• f. 2. 



