190 



collected by Dr. R. Bell in 1879 at the Limestone Rapids, 100 miles up 

 the Nelson River, Keewatin, and a very badly preserved specimen col- 

 lected by Mr. Dowling in 1891 at Dog Head, Lake Winnipeg, are both 

 possibly referable to this meagrely described and badly figured species. 



Pleueotomaria Stokesiana. (N. Sp.) 



Plate 20, figs. 9 and 9a. 



Shell, or rather cast of the interior of the shell, subcorneal, a little 

 broader than high, spire short, umbilicus narrow, nearly or per- 

 haps quite closed when the test is preserved. Volutions about four, 

 though only three are preserved in' the few . .specimens known to the 

 writer, those of the spire flattened obliquely above, with a shallow spiral 

 groove or constriction at the midheight, and obtusely angulated near the 

 suture below : outer volution, as viewed dorsally, higher than the spire, 

 more than twice as broad as high, bluntly angulated at about its mid- 

 height, with a shallowly concave spiral groove just above the angle and 

 convex below, umbilical region rather flattened : slit-band not clearly 

 shewn but apparently occupying the summit of the spiral angulation. 



Surface marked with three small but distinct spiral ridges above the 

 angulation, and with traces of similar but much less distinct ones below, 

 the whole crossed by faint transverse lines of growth. 



West shore of Lake Winnipeg, north of the Saskatchewan, and 

 opposite the north end of Selkirk Island, D. B. Dowling, 1891 : two 

 imperfect casts of the interior of the she^. 



The specific name suggested for this shell is intended as a tribute of 

 respect to the memory of the late Charles Stokes, who was one of the 

 first to describe some of the fossils of the Winnipeg limestones. The 

 only North American fossil from a similar or nearly similar geological 

 horizon that would seem to be at all closely comparable with it, is 

 Cyclonema percarinaium* the Pleurotomaria percarinata of Hall,! but 

 that species is represented as being higher than broad and as encircled 

 with fewer, much more prominent and differently arranged spiral ridges. 



Pledkotomaeia C?) maegaeitoides. (N. Sp.) 



Plate 20, fig. 10. 



Shell very small, turbinate, subglobose, about as broad as high, spire 

 short, umbilicus very narrow in the cast and apparently almost or quite 

 closed when the test is preserved. Volutions probably about four, 

 though only three are preserved in the single specimen known to the 



* Geology of Wisconsin, vol. IV., p. 211, pi. 5, fig. 15. 

 t PalEeontology of New York, vol. I., p. 177, pi. 38, fig. 4. 



