214 PALUDINID^. 



LYOGYRUS, Gill. (Heterocj'^chis, Crosse.) Spire elevated, the 

 last whorl becoming detached from the close spiral near the 

 aperture. U. S., New Caledonia. V.pupoidea, Gould (Ixxiii, 100). 



Family PALUDINID^. 



Shell conical or globular, with a thick, olive-green epidermis ; 

 aperture rounded; peristome continuous, entire. Operculum 

 horny. 



Animal with a broad entire muzzle ; tentacles short and rather 

 stout ; eyes on short pedicels, outside the tentacles. Inhabiting 

 fresh waters in all parts of the world. Dentition (xi, 25). 



Paludina, Lam. 



River-snail. Etym. — Pains (paludis), a marsh. 



Sy7i. — Vivipara, Montf. Yiviparella, Raf. 



Distr. — 100 sp. Fresh water, mostlj^ in the Northern hemi- 

 sphere, Australia.* Fossil, 15 sp. World-wide. Jurassic — . 

 P. Bengalensis, Lam. (Ixxiv, 6). 



Shell turbinated, with round whorls ; aperture slightly angular 

 behind ; peristome continuous, entire. Operculum horny, con- 

 centric. Animal with a long muzzle, and very short eye-pedicels ; 

 neck with a small lappet on the left side, and a larger on the 

 right, folded to form a respiratory siphon ; gill comb-like, single; 

 tongue short; teeth single, oval, slightly hooked and denticu- 

 lated ; uncini 3, oblong, denticulated. The Paludinse are vivi- 

 parous ; the young continuing for some time after they are 

 hatched within the parent shell. 



PALUDINA (restricted). Whorls rounded, generally banded, 

 rather thin, umbilicated. The European species have three 

 bands, those of the United States four bands, whilst the nu- 

 merously banded species are Oriental. 



MELANTHO, Bowdich. Whorls smooth, flattened around their 

 upper portion, generally not banded, solid, nearly or quite 

 imperforate. Peculiar to the United States. P. integra^ Say 

 (Ixxiv, 1). 



TULOTOMA, Hald. Whorls angulated, nodulous, flattened 

 around their upper portion. P. himonilifera^ Lea (Ixxiv, 8). 



MARGARYA, Nevill. Spire produced ; whorls scalariform, with 

 deep suture, sculptured with prominent spiral ribs ; apex obtuse ; 

 rimate. Operculum and animal unknown. Distr-. — P. Melan- 

 oides, Nevill (Ixxiv, 9). Lake Tali, Yunnan. Closely allied to 

 the American subgenus Tulotoma. 



NEOTHAUMA, B. A. Smith. Shell with aperture effuse and 

 slightly channeled at the base ; outer lip rather deeply, yet 



* There are no So. American species, nor in N, Am. west of the Rocky- 

 Mountains . 



