WHITEAVES] LARAMIE AND CRETACEdUS IX VERTEBRATA. f( 



Dawson, ISSl. Fpper Belly Eiver, twentj'-two miles above the mouth 

 of the ^Yaterton, (two left valve-), and Little Bow Eiver, opposite the 

 mouth of Snake Valley-, (one right valve with the tcbt preserved), 

 E. G-. McConnell, IsSl. All from the St. Mary E, Series. 



The lateral compression of the valve- and their extreme obliquity, 

 coupled with the small size and nearly terminal position of the beaks, 

 seem to afford a ready means of distinguishing this shell from the 

 Corhicula occldentalis of Meek and Hayden. 



SPH.ERIU5I RECTicAKDixALE, Meek and Haj'den. 



Sjiharlinn r.ctn.ordinale, Meek and Ha5-den. 18(30. Proc. Ac. Xat. Sc, Phil., voL 



VIII, p. 176. 

 Spli.u-lvm r.rticardinale, Meek. 1S76. Eep. V. Geol. Surv. Terr., vol. IX, p. -527. 



pi., 43, figs. 3, a, b. 



Old Man Eiver, two miles above Eye-Grass flat, G. M. Dawson, 1881 . 

 St. Mary Eiver Series : one nearly perfect specimen and seven single 

 valves. 



(CoRBULA PERUNDATA, Meek and Hayden. 



Corlula pcnnydota, Meek and Havden. 1S.3C. Proc. Ac. Xat. Sc. Phil., vol. 



VIII., p. 110. 

 Corlul'i perundata, Meek. Is7t;. Eep. V. S. Geol. Surv. Terr., vol. IX., p. .530, pi. 



40, figs. 4, a, b, c, d. 



South or First Branch of the 3Iilk Eiver, X. ^V. T,, G. M. Dawson, 

 187-1, H. M. American Boundary Commission : a few single valves 

 from a loose piece of conci-etionary limestone.* According to Dr. C. 

 A. White, C. perundata is only a variety of C. subtrigonalis, M. and H.) 



CoRBULA PERANGULATA. (jST. Sp.) 



Plate 1, ligs. 5, o a and 5 b, and plate 2, fig. 1. 



Shell compressed laterally, moderately convex, thickest a little in 

 front of the middle and narrowing regularly as well as gradually to 

 the posterior end but very abruptly so to the anterio)', so that the 

 outline of the clo-ed valves as seen from above is ovately lanceolate. 



* The.?e are the specimens referred to on page 37 C and in a foot note to page 126 I' of Dr* 

 Dawson's Report on the Bow and Belly River country published in 1S8 



