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preserved on the flat side, there are six of these periodic arrests of growth 

 on the outer volution, while the inner whorls are perfectly smooth. In 

 larger but similarly preserved specimens these arrests of growth, which 

 are not suflSciently deep to produce any impressions on the casts, are 

 somewhat more numerous and disposed ab still more unequal intervals. 

 On the convex side the test is ornamented with rounded spiral ribs of 

 nearly equal size, and these are crossed by straight, transverse costse, in 

 such a way as to present a somewhat nodulous appearance. 



" The foregoing description is intended to apply only to those specimens 

 in which the greater part of the test is preserved. The condition in which 

 the species is usually obtained is that of mere casts of the interior of the 

 shell. In these, the slender early whorls are often broken off, the suture, 

 on the flat side, is deeply excavated or channeled, and, on the convex 

 side, a large portion of the inner whorls is visible in the umbilicus. The 

 whole of the thick test between the volutions is sometimes removed 

 in these casts, in which case the vdlutions are completely separated. 



" In Appendix 1 to the Narrative of Franklin's Second Expedition to 

 the Shores of the Polar Sea, under the heading ' Limestone of Lake 

 Winipeg,' the discovery, among other fossils, of specimens of a Maclurea 

 which is most probably identical with the present species, on the western 

 shore of that lake, in 1825, is thus referred to by Sir John Richardson: — 

 ' Professor Jameson enumerates terebratuloe, orthoceratites, encrinites, 

 caryophyllitce and lingulce, as the organic remains in the specimens 

 brought home by Captain Franklin on his first expedition. Mr. Stokes 

 and Mr. .James De Carle Sowerby have examined those which we pro- 

 cured on the last expedition, and found amongst them terebratulites, 

 spirifers, maclurites and corallines. The maclurites belonging to the same 

 species with specimens from Lakes Erie and Huron, and also from Igloo- 

 lik, are perhaps referable to the Maclurea magna of Le Sueur.' 



" A few casts of the interior of shells which are certainly referable to 

 M. Manitohensis were collected by Mr. John Fleming in 1858 " at Lime- 

 stone or "Clark's Point, Lake Winnipeg, eleven miles north of the Little 

 Saskatchewan, and by Prof. H. Youle Hind, in the same year, at Deer 

 Island, near Grindstone Point and at Punk Island, on the same lake. 

 These specimens, which are still in the Museum of the Survey, are 

 referred to by Mr. E. Billings, in chapter 20 of Prof. Hind's report, as 

 belonging to a species of Maclurea, ' allied to M. Logani, Salter, but with 

 more slender whorls.' 



" Since then the species has been collected at the following localities, but 

 the first specimens known to the writer in which any considerable portion 

 of the test is preserved, were obtained in 1884 by Mr. T. 0. Weston at 

 Pike Head and Kinwow Bay, Lake Winnipeg, and by Mr. McCharles at 

 East Selkirk. Between Fort Alexander and the mouth of the Red River, 



