WHITEAVES.] LARAMIE AND CRETACEOl S rXVERTEBRATA, (17 



South Saskatchewiui, one mile lielow the mouth of tlic Bow River, 

 T. C. Weston, lS>ia : six nearly perfect but somewhat distorteil 

 specimens. 



The lateral outline of this shell is a little like the young examples of 

 Uiiio (/ow/t>/io/'»x figured by Dr. (.'.A. White on plate 26. tigs. 2 c, d, e, of 

 hiv ■■Contributions to Pahpontology." Xos. 2-8 (U.S. Geol. Surv., Wash- 

 ingtoii), but the posterior and postei'odjasal niai-gins of the latter 

 Sjiecies are represented as coarsely plicated and its superior border as 

 forming a subangular junction with the ]iosterior margin behind. The 

 pi-esent species also seems to be nearly- related to the V HaydenI of 

 3Ieek from the Bridger Group of Wj^oming, 



Uxro sEXECTUs. White. 

 Plate 10, fig. -2. 



Cnin scnn-fi'f:. White. 1S77. Bull. U.S. Geol. Surv. Terr., vol. III., p. UOO. 



" " 1>;'^0. U.S. Geol. Surv., (."ontr. to Pal., Nos. 2-S, p. 6!), pi. 



L's, figs. 1 a. b and c. 



White. Iss3. Rev. XonOIarine Foss. :Mo11. N. Am., p. 26, pi. 19, 

 tlus. 1,2. 



South Saskatchewan, one mile below the mouth of the Bow Eivei-, 

 T. (J. Weston. ISS.J : one sjjecimen which measures seventy millimetres 

 in its greatest length by fort}' mm, in its greatest heiglit, and five small 

 specimens the largest of which is thirty-six millimetres loiigand twentj^ 

 high. 



The largest individual collected at this localitj- seems to ditfer a little 

 from the type of f. senectus first figured by Dr. White in being sub- 

 truncated somewhat obliquely at the posterior margin rather than 

 regularly rounde 1, and some <.if the smaller examples (such as the one 

 i-epresented on plate 10) have both umb.inal siojjes on each valve 

 rather distinctly defined. These slight and apparently inconstant 

 variations from the normal torm, however, are obviously not of 

 sjiecific importance. 



(JoRBict;L.\ (jccidentalis. .Mi'ck and llayden. 



(Reference^ to the publications in whii'h this sjjecies was described 

 are given on page 7.) 



Xorth side of the Milk River, five miles below Padvowdci t'oulee, G. M. 

 Dawson, 1831 : a number of well-preserved and nearly iierfect single 



