FLUMINICOLA. 89 



FI^rMINICOtA, Stimpson. 

 Lingual dentition of the type: Rhachidian tooth more than twice 

 as broad as long. Outer lateral teeth with a smaller number of 

 denticles than the inner. Formula of the denticles : 3 f 3 - 6 - 10 - T. 



Fig. 175. 



Lingual dentition of Fluminicola nvttalliana. 



Shell comparatively large, obliquely ovate, thick, smooth, im- 

 perforate ; spire moderate, obtuse. Aperture ovate ; inner lip 

 flattened, callous ; outer lip eifuse and projecting anteriorly, so 

 that the peritreme is not continuously in the same plane. Oper- 

 culum corneous. Tentacles tapering. Rostrum rather large. 

 Foot broad. Terge large, compressed, with a broad semicircular 

 laminiform expansion or wing on its left side. Ova-capsules large, 

 circular, depressed, almost discoidal, each containing a large 

 number of eggs. 



Station, fresh water. 



Distribution, Oregon and California. (Stimpson.) 



Fluminicola iiuttalliaiia, Lea. — Shell subglobose, liorn- 

 colored, smooth ; sutures rather impressed ; whirls 4 ; aper- 

 ture white, nearly round. Fig. 176. 



Wahlamat, near its junction with the Columbia River: 

 Prof. Nuttall. My cabinet ; cabinet of Prof. Nuttall. Diam. 

 .3, length .4 inch. 



There is a very close resemblance between this species and 

 P. nucha (herein described). It is, however, less oblique, Palvdina 

 larger and less elevated in the spire. {Lea.) 



Paludina nuttaUiana, Lea, Tr. Am. Phil. Soc. VI, 101, pi. xxiii, f. 109 



(1839) ; Obs. II, 101. 



Amnicola nuttaUiana, Cooper, P. R. R. Rep. p. 374 (no descr.) (1859). 



Paludina seminalis, HiUDS, Voy. of the Sulphur, p. 59, pi. xvi, f. 22 

 lo 



