WHITEAVES.] LARAMIE AND CRETACEOUS INVERTEBRATA. 65 



TJnio priscus, Meek and Hayden. 



Plate 10, fig. 3. 



Unio pr!iicu^, Meek and Hayden. 18.50. Proc. Ac. Nat. Sr. Phil., vol. VIIL, p. 117. 

 " " Meek. lS7(i. Rep. V. S. Geol. Surv. Terr. vol. IX., p. ,516, pi. 43, figs. 

 S a, b, c, d. 



Belly Eiver, two Biiles above Woodpecker Island, G. M. Dawson, 1881 : 

 an imperfect but beautifully preserved right valve, which is almost 

 certainly spiecifically identical with the similarlj' imperfect specimens 

 fi'om the Laramie of the s^uris Eiver District, already referred to this 

 species on pages 26 and 27. 



The "small, very regular, concentric wrinkles" on the beaks and 

 " the two small, raised radiating lines which extend from the back part 

 of the beaks obliqiiely backward and downward across the jiostero- 

 dorsal region of the immediate umbones," which, according to Meek, 

 are among the distinguishing characters of ?7, j^ir/sats, are extremely 

 well shown in most of the sj^ecimens from the Canadian Laramie and 

 Belly Eiver Series. Both of these characters, however, are said to be 

 common to TJ. priscus an(i to the U. cetusius of Meek from the Beai- Eiver 

 Laramie, but i>n page 165 of the U. S. Geol. Surv. of the 40th Parallel 

 tinder Prof. Clarence King (AVashington, ISY'I), JNIr. Meek states that 

 he has "long suspected " that the latter shell " maj- possibly be iden- 

 tical " with the former. 



A perfect but very immature specimen of a Uido collected iy Mr. 

 Weston in 1883 from the South Saskatchewan, one mile below the 

 mouth of the Bow Eiver, which measures only eighteen millimetres in 

 its greatest length, and which is figured on plate 10, is possibly also 

 referable to T" priscus, though it agrees quite as well with the descrijj- 

 tion of V. vetustus and even better with the figures. 



Unio Dan-t, 3Ieek & Hayden. 



Unio Dmw, Meek & Hayden. 1857. Proc. Ac. Xat. Sc. Phil., vol. I.X., p. 145. 



" Meek. 1870. Rep. U. S. Geol. Surv. Terr., vol. IX,, p. 517, pi. 41, figs. 

 13, a, b, c. 



Belly Eiver, north-west angle of Driftwood Bend, G. M. Dawson, 

 1881 : abundant, typical and well preserved. 



August, 188.5. 5 



