PLANORBIS. 489 



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



— H.vLDEMAN, Mon. 13, pi. 2, figs. 4-7 (1844). — Adams, Shells of Vt. 154 (1842). 



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

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



fig. (1857). — W. G. BiNNEY, Smith. Inst. L. and Fr. W. Shells, ii. 115, figs. 194- 

 201 (1865). 



Bulla flitviatili.% Sat, Jonrn. Acad. Nat. Sc. ii. 178 ; ed. Binney, 71. 



P/anorhis reijuhiris, Lea, Tr. Am riiil. Soc. ix. 6 ; Proc. ii. 32 (1841) ; Obs. iv. 6, 



Planorbis megnstoma, De Kat, N. Y. JNIoll. 61, pi. 4. figs. 60, 61 (1843). 



Phjisa plam'rbula, De Kay, N. Y. Moll. 76, pi. 5, fig. 83 (1843). 



Planorbis cor put cut us, De Kay, N. Y. Moll. 64, pi. 13, fig. 185 (1843). — Wiiittemorb, 



Am. Journ. Sc. [i], xxxviii. 103. 

 ? Planorbis proboscideus, Potiez and Michadd, Gal. des Moll. i. 213, pi. 25, figs. 13 - 15 



(1838). 

 Planorbis mucrostomus, Whiteaves, Can. Nat. viii. 113, fig. (1863). 

 Planorbis trivolvis, va.r.fallax, Haldeman, Mon. 15, pi. 3, figs. 1-3 (1844) 

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

 Helix triroh-is, Eaton, Zool. Text Book, 194 (1826). 

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



16. 



Shell orbicular, yellowish-wliite, brownish, or chestnut color ; um- 

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

 on the right side scarcely three volutions, -seijarated 'LJL^ 



by a profound suture, are visible as they disappear /^ ' ■' '''% 

 in the umbilicus, their faces, especially those of the k^ M'^>) S 

 interior whorls, being slightly carinated ; on the left ^^\&!;'w:^ 

 side at least four whorls are seen, which, by their ^^ — _>iiik^^ 



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



guished by the suture, except the last half of the , /iB, 



outer whorl, on the whole of which a well-marked i :'|m WiiJln 

 carina revolves, forming a margin to the cup ; the ^^T^^j^-" * 

 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 



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

 considered dextral. — W. G. B. 



