140 LAND AND FRESH- WATER SHELLS OF N. A. [PART IL 



worth (in Berne Mittlieil., 185-4, p. 98) quotes it from St. Thomas, 

 Jamaica, and Porto Ilico. 



Aiicylus fHSCUS, Adams. — Shell thin, transparent without the epi- 

 dermis, not much elevated, elliptical, moderately curved at the sides ; epi- 

 dermis brown, visible through the shell, giving it the appearance of having 

 the same color, thick, rough, slightly extending beyond the 

 Fig. 233. margin of the shell ; apex obtuse, moderately prominent, 

 ^^^,.^ scarcely behind the middle, inclining to the right so as to have 

 only two-fifths of the width on that side. Length .31 inch, 

 fuscus width .22 inch, height .05 inch. Cabinets of Bost. Soc. Nat. 



Hist., of Mr. Kinne Prescott of Andover, and my own. 

 Habitat and station. This species was found adhering to stones in a 

 small rivulet, at Andover, by Mr. Kinne Prescott, to whom I am indebted 

 for many interesting species of shells. It has also been found at Mansfield. 

 This species is easily distinguished by its epidermis. The A. rivularis. 

 Say, diflfers also in being much more narrow, having its sides straight, and 

 its apex more acute ; and A. tardus, Say, is more elevated, and in both 

 of these the apex does not incline so far to the right as in our species, 

 'ilie A. lacustris, Drap., is more narrow, with an apex more elevated and 

 acute, and A. Jiuviatilis, Drap., has the apex more prominent and nearer 

 one extremity. (^Adams.) 



Ancylus fuscus, Adajis, Bost. Journ. Nat. Hist. HI, 329, pi. iii, f. 17 

 (1840); Am. Journ. Sc. [i], XXXVIII, 396 (1840). — Haldeman, 

 Hon. 12, pi. i, f. 7 (1844).— Gould, Iuv. 224, f. 1.'32 (1841).— DeKay, 

 N. Y. Moll. 13 (1843).— Ax\o>'Y. Can. Nat. II, 212, fig. (1857). 



The original desci-iption and figure are copied above. It has 

 also been found in Ohio and the District of Columbia. 



Aucylus elatior, A^fTnoNY. — Sliell very much elevated, ovate ; 



lines of growth distant, conspicuous : color light green, opaque ; apex de- 



cuticated, recurved, sub-central ; anterior and posterior 



Fig. 234. slopes convex ; lateral slopes plane ; apical region rose 



colored. 



J/iib. Green Kiver, Kentucky, adhering to small 

 stones and dead shells. Very rare. My cabinet ; 

 J noylus elatior. cab. Lyc. N. H. Length .23 inch (6.} mill.), breadth 



0.21 inch (5 mill.), height .14 (3^ mill.). 

 Ohs. This is rather a heavy, robust species, and one not easily con- 

 founded with any other ; it most nearly resembles, perhaps, Ancylus crassus. 



