8 PALUDINIDiE. 



tentacula, the extremities of which are setaceous, but the 

 bases thickenefl by the union with them of the eye- 

 peduncles. Tentacles of male unequal. Bisexual. Male 

 organ concealed in the right tentacle. Mantle ample. A 

 small veil on each side of the neck. Foot large, oblongo- 

 triangular, obtuse and not grooved behind, bearing on a 

 rounded lobe an operculum, which is corneous and com- 

 posed of concentric elements around a central nucleus. 

 Branchial plume single, concealed. Tongue very short, 

 armed with transverse series of denticles, each composed 

 of an ovate central denticle flanked on each side by three 

 oblong lateral uncini, all with crenated apices. 



The females of the Mollusks of this genus are ovo- vivi- 

 parous. In autumn, according to the observations of M. 

 Bouchard-Chantereaux,* they contain each twenty or 

 thirty eggs. The young fry are not sent adrift by their 

 parent until the end of the second month of their exist- 

 ence, by which time the bands of cilia which cover their 

 shells have disappeared. Two, three, or four only are 

 absolved from their mother's care in twenty-four hours, so 

 that the entire family of a Paludina take some time before 

 beginning to make their way in the world. 



P. LisTERi, Forbes and Hanley. 



Abbreviated ; whorls very and abruptly tumid ; umbilicus 

 large and open. 



Plate LXXI.fig. 16. 



Ilelioe vivipara (not of Linn.), Schroter, Fliissconch. p. 330 (in part), pi. 8, 

 f. 2.~Da Costa, Brit. Conch, p. 81, pi. 6, f. 2.— Donov. 

 Brit. Shells, vol. iii. pi. 87. — Mont. Test. Brit. p. 386, and 



* Memoires de la Soc. d'Agriciilt., &c. de Boulogne-siir-Mer. 2nd Series, 

 vol. i. p. 217. 



