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



Planorhis ohUquus, DeKay, N. Y. Moll. G2, pi. iv, f. 57 a, h (1843). 

 Nautilina dcjlecta, Chexu, Man. de Concli. II, 482, f. 3566. 



This species is said to range from great Slave Lake to tlie 

 District of Columbia, and from New England to Nebraska. 



Mr. Say's type is still preserved in the Philadelphia Academy. 



I am inclined to place P. ohliquus in the synonymy of P. de- 

 Jlectus. PI. virens is so considered by both Gould and Halde- 

 man. Copies of the original descriptions and figures here follow : — 



Planorhis virens. — Shell small, greenish horn-color, with thick, obvious 

 striK of growth, and very slight revolving lines, with a green rough epi- 

 dermis ; whirls four ; siiture impressed ; spire not rising above the last 

 whirl, but scarcely falling below it ; last whirl much larger 

 Fig. 216. than the spire, flattened above, then abruptly curving down- 

 wards (in the young shell, at the upper third of the last whirl, 

 is a carina, which is gradually modified into the abrupt curva- 

 ' '■ ture, in the progress of growth), subcarinate below, as are also 



(@) } the preceding whirls; aperture nearly orbicular, interrupted 



by the last whirl in about one-fifth of its circumference, ad- 

 vancing above ; umbilicus as broad as the last whirl, rather 

 virens. ^ 



deep, exhibiting all the volutions. Height (of the last whirl) 



.09 inch, greatest breadth .23 inch, least breadth .18 inch. Cabinets of the 

 Bost. Soc. Nat. Hist., of Middlebury College, of Mr. Shiverick, and my own. 



Habitat. New Bedford. 



For this species I am indebted to Mr. Shiverick. It differs from P. parvus, 

 Say, in being much less broadly and more deeply umbilicate beneath ; it 

 is also higher. P. parvus, also, instead of being subcarinate on the lower 

 side of the whirls is much flattened. P. concavus, Anthony MSS., resembles 

 this species, but is more regularly convex above and concave beneath. 

 (^Adams.) 



Planorhis ohilqutis, DeKay. — Shell depressed, discoidal. Volutions four ; 

 the surface shining, with regular minute incremental lines ; the body whirl 

 obsoletely subangular below. Spire nearly as much depressed 

 Fit;. 217. ^^ *^^® umbilicus, which latter is large and exhibits all the 

 volutions to the apex ; suture distinct ; body whirl not dis- 

 tinctly deflected from the plane of the other volutions. Mouth 

 unarmed, very oblique. Color dull olive. Diameter 0.3, 

 height 0.1. 



The specimens of this species were obtained from the Mo- 

 hawk and from Newcomb's Pond, in Pittstown, and presented 

 )iy Dr. B. W. Budd, of this city. Some eminent conchologists suppose it 

 t>i be a variety of the dcjlectus of Say; but from this it differs by the 

 oMirjuity of the mouth when turned downwards, apd has no acute lateral 

 edge as in that species. The concavus of Anthony, of which I have seen 



