PERISTOMIDA. 3 



Genus II.— PALUDINA^Lamarck. 



Shell ovate, or oblong; spire somewhat turreted ; the volu- 

 tions smooth, rounded, and subcarinated ; aperture subrotund, 

 ovate, or oblong, a little angulated above, slightly modified on 

 the inner side by the gibbosity of the body volution ; lips united 

 all round, with acute edges; operculum corneus, with concentric 

 lines of growth, and provided with a sublateral nucleus. 



1. Paludina vivipaha, pi. I, f. 4, 5. 



Paludina vivipara, Lamarck, An. San. Vert., VI, pt. 2nd, p. 

 173 ; Brard, Coq. de Paris, p. 174, pi. 7, f. 1 ; Fleming, Brit. 

 An., p. 315 ; Alder, Mag. Zool. and Bot., II, p. 116; Thomp- 

 son, Ann. and Mag. Nat. Hist., p. 17; Brown, Illust. Conch., 

 p. 26, pi. 14, f. 71, 72; Cyclostoina viviparum, Drapernaud, 

 Hist. Nat. des Moll., p. 34, pi. 1, f. 16, 17; Turton, Man., 

 p. 113, f. 118; Brard, Coq. de Paris, p. 174, pi. 7, f. 1 ; Ross- 

 massler, f. QQ ; Helix vivipara, Montagu, Test. Brit., p. 386 ; 

 Brown, Wernerian Mem., II, p. 527 ; Viviparus jluviorum, 

 De Montford, II, p. 247 ; Paludina achatina, Sowerby, Gen., 

 f. I. 



Shell thin, subconic, oblong-ovate; spire consisting of five 

 extremely ventricose, abruptly diminishing volutions, separated 

 by a deep suture, and terminating in an acute apex ; aperture 

 suborbicular, a little contracted above ; pillar lip slightly reflect- 

 ed, behind which is a subumbilicus; inside smooth, bluish-white, 

 the external bands shining through ; whole shell covered with 

 an olive-green shining epidermis, beneath which the shell is 

 white, with three spiral, dark brown bands on the body, and two 

 on the superior volutions, which generally grow fainter as they 

 ascend, until they become nearly invisible before reaching the 

 apex ; surface slightly wrinkled longitudinally, several of which 

 are coarser than the others, marking the periodical growth of 

 the shell ; aperture protected by a thin horny operculum. 



In the young condition the shell is subglobose, subpellucid, 

 with the bands rather obscure, and the volutions appear more 

 flattened above than in the adult state. 



Found in the Thames and other slow rivers, and sometimes 

 in ponds. Plentiful in a ditch near Southport, Lancashire. 

 Occurs in a stream at Newtownards, County of Down, 

 Ireland. 



