lU 



LAND AND FRESH-WATER SHELLS OF X. A. [PART H. 



The above description and figure are copied from Chemnitz, 

 ed. 2. 



Fig. 190. 



Planorbis corpuleiitlis, Sat.— Shell dextral ; whirls more than 

 three, rather rugged with coarse wrinkles, much higher than wide ; supe- 

 rior surface much flattened, and edged by an abrupt acute line, which is 

 distinct to the aperture ; 'sides hardly rounded and ter- 

 minating below by another abrupt edge, which is not 

 quite so definite and acute as the superior one; spire 

 slightly concave ; umbilicus exhibiting a portion of each 

 of the rapidly retiring whirls to the apex ; aperture 

 longer than wide, the superior part extending higher 

 than the preceding volution, and the inferior volution 

 declining much lower than the inferior line of the same 

 volution. Greatest breadth three-fourths of an inch ; 

 length of 'aperture nearly half an inch ; length of the 

 penultimate whirl near the aj^erture rather more than 

 three-tenths of an inch. 



Inhabits Winnepeck River, Winnepeck Lake, Lake 

 of the Woods, and Rainy Lake ; common. 

 Of this species I collected numerous specimens, but had the misfortune 

 to lose them all, as well as a great number of interesting terrestrial and 

 fluviatile shells, on our return to the settlements, and I am indebted to 

 the liberality of Dr. Bigsby for the individual above described. It is 

 closely allied to tricolvis, Nob., but is much less rounded on the sides of 

 the whirls, the carinse are more prominent, the upper side is much more 

 horizontally flattened, the labrum is less rounded, and the whole shell is 

 larger and higher in proportion to its width, and the aperture extends both 

 above and below the penultimate whirl. (Sai/.) 



Planorbis rorpuhntus, Say, Long's Ex. II, 262, pi. xv, f. 9 (1824) : Bin- 

 ney's ed. p. 128, pi. Isxiv, f. 9.— ? Haldeman, Mon. 19, pi. iii, f. 7-9 

 (1844).— ?GonLD, U. S. Ex. Ex. Moll. 114, f. 130, 130 m, 130 6 

 (1852). 



?Helisoma corpulcnta, Chenu, Man. de Conch. II, 482, f. 3560. 



Animal dark emerald green, profusely dotted above and below 

 with small white points, paler beneath. Jlead large, tentacles 

 very slender. (Gould.) See Fig. 175, p. 103. 



I am inclined to believe that Say had before him a form of 

 Plan. t7-irolfis when he drew his descrijjtion of Flan, corpu- 



