WHiTEAvEs] DEVONIAN FOSSILS OF MANITOBA, ETC. 333 



Natica occurs as far back as the Silurian epoch, and the recent discovery 

 of paucispiral and possibly naticoid opercula in the Guelph limestone of 

 Ontario seems to the writer to afford strong presumptive evidence of the 

 correctness of this conclusion. Still, as the occurrence of tha geims, NiUica 

 or of any of its subgenera, in rocks of Paheozoic age, cannot at present be 

 satisfactorily proved, it is thought better to refer this and the next species 

 to jVdficopsis. 



The surface markings of the present species appear to be essentially 

 similar to those of the JVaticopsis oiquisfriata of Meek,* from the Cor- 

 niferous limestone of Ohio, and of the Natica untiqua of Goldfuss,t from the 

 Devonian rocks of Germany and England. According to Mr. Meek, how- 

 ever, the Saticojysit: mquistriala is less than five millimetres in height, 

 broader than high, with a depressed spire. Natica anfiqua, also, has a 

 shorter spire than that of Naticopsis Manitohensis, and a much more 

 expanded outer volution. 



(S.) Naticopsis inornata. (N. Sp.) 



Plate 43, flg. 14. 



Shell imperforate, ovately subglobose, the height and breadth being 

 nearly equal, spire short, conical, occupying rather more than one-sixth 

 of the entire height. Volutions about four, increasing rapidly in size, 

 those of the spire obliquely compressed, the outer one large, obliquely 

 expanding and increasing rapidly in height, as well as breadth, toward 

 the aperture, its base narrowly rounded and somewhat produced : aper- 

 ture subovate, outer lip thin and simple. 



Surface nearly smooth, and showing only a few obscure lines of growth. 



Dimensions of the largest and most perfect specimen obtained, the one 



figured : maximum height and greatest breadth, each about twenty-three 



millimetres and a half : height of spire, as measured on the median line 



of the dorsal surface, four mm. 



Dawson Bay, Lake Winnipegosis, on a, small island north north-west 

 of Beardy Island, J. B. Tyrrell, 1889 : one nearly perfect specimen, with 

 the test preserved, the original of fig. 14 on plate xliii. A few casts of 

 the interior or moulds of the exterior of shells apparently referable 

 to this species, were collected by Messrs. Tyrrell and Dowling, in 1889, 

 in Dawson Bay, at Whiteaves Point, on a small island three miles north 

 of Salt Point, at the mouth of Steep Rock River, about two miles west of 

 Salt Point, and at the first small point north of the mouth of the Red 

 Deer River. 



*GeoI. Surv. Ohio, 1873, vol. I, pt. 2, p. 216, wood outs a, b. 

 tPetref. Germ., vol. Ill, 1841-44, p. 117, pi. cxcix, figs. 2 a, b. 



