S CONTRIBUTIOXS TO CA^'ADIAX PAL.EONTOLOGT. 



Oyster Creek, X. W. branch of the north fork of the Okl Man Eiver r 

 G. M. Dawson, 1SS4. See note to same phieo under Ostrea glabra. 

 Eed Deer Eiver, near the 8th correction line,— and forks of the Devil's 

 Pine and Three Hills Creeks ; J. B. Tyrrell, 1SS4. 



The specimens from the~e localities, which are somewhat variable 

 in shape, appear to be nearly intermediate in their characters between 

 C. occidrntalis and C. ctjtheriformis, anil it is doubtful to which of these 

 si.ecie> they -hould be referred. According to Meek, the bhell of C. 

 occidentaVs is " subtrigonal in form, with height and length about equal," 

 whereas that of C. cytheriforinis is said to be "transversely ovate sub- 

 trigonal, or varying to sub-circular, but always a little longer than high.' 

 In the Canadian specimen--, some of which are very perfect and mea- 

 sure fully one inch and three quarters in their two lateral diameters, 

 the outline is distinctly subtrigonal and the height and length are 

 either equal or else the height slightly exceeds the length. As com- 

 pared also with the published figures of the two species, the specimens 

 from the Canadian Xorth-West are much more like those of C. occiden- 

 talis than those of C. cytheriforinis. 



COKBICCLA OBLIQUA. (N. Sp.) 

 Plate 1, figs. 4, -ia and 4 b. 



Sliell comjjressed convex, the thickness through the closed valves 

 being about one-third less than the maximum height inclusive of the 

 beaks : obliquely sub-ovate, usually a little longer than high and very 

 iijcquilateral. Antei'ior side extremeh" short, its margin either slightly 

 coricave or vertical!}- truncated under the beaks al'ove, and rounding 

 abruptly or declining rapidl}' and convexly into the ventral margin 

 below ■ jjosteiior side moderately elongated, obtusely pointed at the 

 base, its upper margin forming one continuous, obliquely convex curve 

 wliich extends from the beaks to the base; ventral margin semi- 

 ovate. Beaks small, anterior and nearly or quite terminal, almost 

 eiL'Ct, their extreme apices onlj- being curved inwards, forwards and a 

 lit lie downwards. 



Surface concentrically striated: characters of the interior unknown. 



Length of the most perfect specimen collected, twentj'-six milli- 

 meti-es : maximum height of the same, twenty-two mm. ; thickness 

 through the closed calves, fifteen mm. 



Rye-Grass flat, Old Man Eivei-, (one perfect specimen, with the 

 test preserved on both valves) and Bow Eivei-, eight miles west of 

 Blackfoot Crossing, (a well pix-crved cast of a left valve), G. M. 



