Trenton Gasteropoda of Manitoba. 319 
American fossils which had then been referred to P. lenti- 
cularis, Sowerby, are distinct from that species, and in the 
following year H. billings maintained that three species, 
which he then described and figured under the names 
Pleurotomaria Progne, P. Americana and P. Helena, had been 
mistaken for the true P. lenticularis. 'The specimens so far 
collected in Manitoba are too imperfect to be identified with 
much certainty, but they all appear to belong to the form 
which Billings proposed to distinguish as P. Americana. 
Lindstrém, on page 108 of his valuable monograph “on 
the Silurian Gasteropoda and Pteropoda of Gothland,” states 
that the shell which Conrad figured as P. lenticularis, 
Sowerby, in 1848, in Emmons’ Geological Report of the 
Third District of the State of New York, is P. qualteriata, 
Schlotheim, and that it is “quite different” from thé 
P. lenticularis of Hall. 
PLEUROTOMARIA SUBCONICA. 
Pleurotomaria subconica, Hall. 1847. Pal. St. N. York, vol. 1, pp. 174 
and; 304, piss xxxvil, = figs) Shc 
XxXxvili, fig. 3. 
«“ « Billings. 1863. Geol. Canada, p. 180, fig, 
174. 
Me & Whitfield. 1882. Geol. Wiscons., vol. 1v. 
p. 216, pl. vi, fig. 1 
_ The Dog’s Head (two specimens), and Stony Point (one 
specimen), Lake Winnipeg, T. C. Weston, 1884. 
PLEUROTOMARIA MURALIS. 
Pleurotomaria muralis, D. D. Owen. 1852. Rep. Geol. Surv. Wisc., 
Towa and Minn., p. 581, pl. ii, fig. 6. 
“Lower Fort Garry, Red River of the North,” Owen 
(op. cit., p. 626). A natural mould of the exterior of the 
est of the upper portion of a specimen, collected by Dr. R. 
Bell, in 1879, at the Limestone Rapid 100 miles up the 
Nelson River, Keewatin, and a very badly preserved speci- 
men collected by Mr. Dowling, in 1891, at the Dog’s Head, 
Lake Winnipeg, are both possibly referable to this species. 
