176 



Orthis pectinella, Hall 1883. Second Ann. Rep. N. York St. G-eol., 



pi. 34, figs. 39 and 40. 

 II M vax-semiovalis, S. A. Miller. 1889. N. Am. Geol. and Palaeont., p. 359. 



Dinorthis pectinella, Hall 1892. Pal. N. York, vol. VIII., pt. 1, pp. 



195, 222 and 228, pi. 5, figs. 27-33. 

 Orthis (Dinorthis) pectinella, Wmchell and 



Schuchert 1893. Lower Silur. Brach. Minn., p. 424, 



pi. 32, figs. 31-34. 



Lake Winnipeg, at the north end of Punk Island, D. B. Dowling, 

 1890: one imperfect but characteristic ventral valve. 



Oethis (Dinorthis) sdbquadeata, Hall. 



Orthis suhquadrata. Hall 1847. Pal. N. York, vol. I., p. 126, pi. 32 A, 



fig. 1. 



„ 1862. Geol. Wisoons., vol. I., p. 54, figs. 1 



and % 



„ „ Billings 1863. Geol. Canada, p. 165, figs. 146, a-l. 



Meek 1873. Rep. Geo!. Surv. Ohio, vol. I., pt. 2, 



p. 94, pi. 9, fig. 2 : and of subsequent 

 writers on N. Anier. paleeontology. 



Orthis (Plcesimnys) snhquadrata. Hall 1892. Pal. N. York, vol. VIII., pt. 1, pp. 



194, 197, and 222, pi. 5 .i, figs. 17-19. 

 Orthis (Dinorthis) suhqwidrata, Winchell 



and Schuchert 1893. Lower Silur. Brach. Minn., p. 428, 



pi. 32, figs. 46-50. 



Lake Winnipeg, at Little Black Island, and Snake Island, D. B. 

 Dowling and L. M. Lambs, 1890; on the west shore, north of the Sas- 

 katchewan and opposite the north end of Selkirk Island, — and at the 

 First Limestone Point north of the Saskatchewan, D. B. Dowling, 1891. 



Orthis (Dinorthis) proa vita 1 Winchell and Schuchert. 



Orthis 2^roavita, Winchell and Schuchert. . . .1892. (Aiirill). Amer. Geol.,vr>l. IX., p. 290. 



11 pctrw, Sardeson ^892. (April 9). Bull, ilinn. Ac. Nat. Sc, 



vol. IIL, p. 332, pi. .5, figs. 18-21. 

 Orthis f Dinorthis) proavita, Winchell and 



Schuchert 1893. Lower Silur. Brach. Minn., p. 431, pi. 



32, figs. 51-,57. 



Orthis ( Dinorthis) proavita, Whiteaves 1895. This volume, pt. 2, p. 120. 



A few imperfect natural moulds of the exterior of shfUs of a coarsely 

 ribbed subquadrate Orthis, which are possibly referable to this species, 

 were collected by Mr. Dowling in 1891 at Dancing Point and Selkirk 

 Island, Lake Winnipeg, also on the west shore of the lake opposite the 

 north end of Selkirk Island. Gutta percha squeezes from these moulds 

 are essentially similar in form and sculpture to specimens of the large 

 variety of 0. proavita from Stony Mountain, but none of these squeezes 

 shew any portion of the hinge area, or anything but the sculpture and 

 general outline of imperfect detached valves. 



