PLANORBIS. 



489 



y. Moll. 59, pi. 4, fig. 59, a, b (1843). — Gould, Inv. of Mass. 201, fig. 131 (1841 ). 



— II,vLi)E.M.\N, Mon. 13, pi. 2, figs. 4-7 (1844). — Adams, Shells of Vt. 1.54 (1842). 



— KusTEU, in Chemn. 2d ed. 53, pi. 5, figs. 4 - 6 ; pi. G, figs. 1 - 6, 20 - 25. — Potiez 

 et MiciiAUD, Gal. dcs Moll. i. 214, jd. 21, figs. 19-21. — Anon. Can. Nat. ii. 202, 



fig. (18.J7). — \V. G. BiNNEY, Smith. Inst. L. and Fr. W. Shells, ii. 115, figs. 194- 

 201 (18G5). 



Bulla fluvlatilts, Say, Jonrn. Acad. Nat. Sc. ii. 178 ; cd. Binney, 71. 



Planorbls rojularis, Lea, Tr. Am Phil. Soc. ix. 6 ; Proc. ii. 32 (1841) ; Obs. iv. 6. 



P/anorbis mrqastoma, De Kay, N. Y. Moll. 61, pi. 4. figs. 60, 61 (1843). 



Physa planorbiila, De Kay, N. Y. Moll. 76, pi. 5, fig. 83 (1843). 



Phinorbis corpukntus, De K\y, N. Y. Moll. 64, pi. 13, fig. 185 (1843). — Whittemore, 



Am. Jouvn. Sc. [i], xxxviii. 193. 

 ? Planorbis probuscideus, PoriEZ and Michaud, Gal. des Moll. i. 213, pi. 25, figs. 13 - 15 



(1838). 

 Planorbis macrosf.omus, Wiiiteaves, Can. Nat. viii. 113, fig. (1863). 

 Planorbis trivolcis, var. fallax, Haldeman, Mon. 15, pi. 3, figs. 1 -3 (1844) 

 ? Planorbis lentus, Gould, Inv. 202, fig. 132 (1841). 

 Helix trivolvis, Eaton, Zool. Text Book, 194 (1826). 

 Cochlea trium orbum, Lister, Conch, pi. 140, fig. 46. — Petiver, Gazophyl. pi. 106, fig. 



16, 



Shell orbicular, yellowisli-wliitc, brownish, or chestnut color ; uni- 

 bilicated on the right side, cup-shaped on the left ; 

 on the right side scarcely three volutions, separated 

 by a profound suture, are visible as they disappear 

 in the umbilicus, their faces, especially those of the 

 interior whorls, being slightly carinated ; on the left 

 side at least four whorls are seen, which, by their 

 faces, form a cup-shaped depression, scarcely distin- 

 guished by the suture, except the last half of the 

 outer whorl, on the whole of which a well-marked 

 carina revolves, forming a margin to the cup ; the 

 carina gives the whorl a flattened appearance on 

 this side ; surface covered with fine, regular, raised, transverse 

 lines, somewhat grooved between them ; aperture sub-ovate, inclin- 

 ing to the right, its right margin more advanced than the left, 

 broadly and regularly rounded ; left lip abruptly angulated where 

 the carina terminates ; lip usually thickened within, and of a red- 

 dish-brown color. Large diameter, seven tenths of an inch ; small 

 diameter three tenths of an inch. 



Animal dark russet or dusky, covered with pale yellowish dots. 



Found in the western parts of this State in rivers and ponds. It 

 is widely extended over the Northern and Western States. 



Planorbis corpulentus of Say seems little else than an exuberant 



Fig. 740. 



p. Irivolvis.* 



* I arrange the figures as in Dr. Gould's plates, though the shells of the genus are now 

 considered dextral. — W. G. B. 



