40 CONTRIBUTIONS TO CANADIAN PALyBONTOLOGT. 



Ctprina ovata, Meek and Hayden. 



C'liprina orata, Meek and Hayden. 1857. Proc. Ac. Xat. Sc, Phil., vol. IX., p. lU. 

 " Meek. 1876. Eep. U.S. Gaol. Surv. Terr., vol. IX., p. 146, pi. 129, 

 figs. 7 a, b, c, and woodcut, fig. 8. 



y.utiETY ALTA. (Var. nov.) Plate 5, fig. 3. 



Shorter than the typical form and broader in the dii-ection of its 

 height. 



Belly Eiver, near and a little west of the mouth of St. Mary Eiver, 

 also below Horso Shoe Bend, G-. M. Dawson and E. G. McConnell, 

 1881 ; St. Mary Eiver, near its coniiuence with the Belly Eiver, G. M. 

 Dawson, 1881, and T. C. Weston, 1883 : extremely abundant and well 

 preserved at each of these localities, the prevalent form being appa- 

 rently the var. alta. 



St. Mary Eiver, west of MacLeod Benton Trail, E. G. McConnell, 

 1881, mostly the var. alta. South Saskatchewan, opposite Swift Cur- 

 rent Ci-eek, E. G. McConnell, 1882 : the typical form apparently most 

 prevalent. Eoss Couli^e, near Irvine Station, on the Canadian Pacific 

 Eailway, T. C. "Weston, 1884 : many casts of the interior of shells of 

 the typical form and a few of the car. alta. 



An exceedingly abundant and characteristic species in the Canadian 

 North-west. The specimens are often very perfect and beautifully 

 preserved, and the variety alta seems more common than the type, 

 though the two forms are usually if not invariably fjund associated 

 together at each of the localities fi'om which the species has been col- 

 lected. 



CoRBiCDLA occidentalis. Meek and Hayden. 



(For the synonymy, &c., of this species see page 7). 



A few imperfect and badly preserved specimens of a Corbicula which. 

 are apparently referable to this species were collected by Dr. G. M. 

 Dawson in 188.3, at the base of the Fort Pierre Group, at lElk Eiver 

 Eidge, associated with an abundance of Ostrea subtrigonalis, and with 

 a fragment of a Unio. 



