PLA.TE VIII {continued). 



6. — Paludina decisa, River Potomac, U.S. Narrow band, witli numerous 

 minute teeth ; medians and lateral differing slightly. Median 

 refl.ex.ed, denticulate. Laterals similar, narrower and smaller 

 denticulatious. 



7. — Faludlna vivipara, Brit. Mounted in balsam, and rendered thereby 

 much too transparent. Median subquadrate, produced outwardly, 

 refiexed, denticulate. 1st, 2iid, and 3rd laterals narrower, reflexed, 

 and denticulate. 



8. — Lacuna puteolus, Brit. Median broadest, five-cuspid. Laterals, 1st and 

 2ud denticulate; 3rd simple, hooked, omitted in drawing. 



9. — Vahata cristata, Brit., Suffolk. Very minute band, about one fiftieth 

 of an inch. Median broad, reflexed, denticulate. Laterals similar, 

 reflexed, and denticulate. 



10. — Mandible or buccal plate of V. cristata iu two equal parts, armed with 

 numerous rows of simple spines. 



11. — Cistula catenata, Germany, Dr. Troschel. Median small, narrow, 

 reflexed; cusp apical. 1st lateral bold; cusp much produced. 

 2nd lateral broad, denticulate; uneini numerous. This, named 

 by Gray Cistula, evidently belongs to Cyclostomidse. 



12. — TropidopJiora artiodata, Rodriquez. So named by Troschel ; clearly 

 belongs to Cyclostoma. A large narrow band of well-arranged 

 teeth. Median large, subquadrate, produced outwards, reflexed, 

 denticulate. 1st and 2nd laterals similar, denticulate. 3rd, nume- 

 rous fine serrations extending down outer border. 



13. — Pileopsis Eungaricus. Belonging to Calyptra^idse (bonnet-limpets), 

 found chiefly on oysters. Dentition is seen to be almost identical 

 with velutina. Drawn from my friend Mr. F. Walker's collection. 



14. — Bybocydis gravidum, Manlmein. It appears doubtful whether this 

 should not be named Cyclotus rugatus. Median broad, produced 

 outwards, tridentate. 1st lateral produced outwards, bidentate. 

 2nd lateral similar, but shorter. 3rd still smaller, teeth diminishing 

 outwards. 



\b.—II. gravidim. Mandible iu two equal parts ; numerous rows of finely 

 acute spines, gradually diminishing. 



16. — Lacuna vineta. Median quadrate, reflexed, tridentate. 1st and 2nd 

 laterals produced outwards, denticulate; 3rd believed to be simple, 

 but cannot be made out in specimen. 



17. — Ci/clophorus aquilum, Burmah. Belonging to operculated land-snails. 

 Odontofore a narrow, elegant ribbon. Median reilexed, tridentate. 

 1st lateral looks inwards, tridentate; 2nd and 3rd sickle-shaped; 

 base flattened out, and set firmly in basement membrane. Man- 

 dible large and bold, covered with acute spines placed iu numerous 

 regular rows. 



"o' 



PLATE IX. 



Taenioglossa. 



■'»' 



18. — Melania multilineata, R. Potomac. A long and minute band of fine 

 teeth. Median reflexed, and cuspid ; centre cusp long. 1st 

 lateral reflexed, broad on the upper edge, and multicuspid ; 2ud 

 and 3rd reflexed, muliicuspid. 



