wrnns.] CEOW CREEK FOSSILS. 169 



at that locality, and -svas obtained only from No. 3 of the section. It is 

 described in tlie Bulletin of the Geological and Geographical Survey of 

 the Territories, vol. iv, p. 711. 



1^0. 8. Corhicula obcsa AVhite. 



This species has been discovered both in Crow Creek and Bijou Creek 

 valleys, but not elsewhere. It conies from No. 3 of the Crov/ Creek sec- 

 tion. It is described in the Bulletin of the Geological and Geographical 

 Sur\'ey of the Territories, vol. iv, j). 712. 



Xo. 0. Corhicula cardinicvformls White. 



This is a rare but well-marked species. It was found only iu bed No. 

 ?} of the Crow Creek section, and is described in the Bulletin of the 

 Geological and Geographical Survey of the Territories, vol. iv, p. 711. 



No. 10. Corhicula {Leptesthes) suhelliptica Meek & Ilaydeu. 



Dr. Ilayden originally discovered this S]i8cics in the valley of Cherrj'- 

 Creek, Dalcota, in beds that both he and Meek referred either to the 

 Fort Union or Judith River series, but were unable to decide which. 

 While at tlie original localities these two groups seem to be sufficiently 

 distinct, subsequent discoveries (most of which are presented iu this 

 rei^ort) of the fossils' of each group associated in the same layers else- 

 v>here make it doubtful whether they will ever be recognized as dis- 

 tinct groups elsewliere than at the original localities. C. {L.) HuheUlptlca 

 is described and figured in vol. ix of the United States Geological Sur- 

 vey ; and Mr. Meek there refers to this species as having been found in 

 the valley of Bijou Creek (where I also found it), as well as in the Upper 

 Missoiui liiver region. It comes from bed No. 3 of the Crow Creek sec- 

 tion, where it is associated with several other species of that genus. 



No. 11. Corhicula {Leptesthes) fracta Meek. 



Several imi:>erfect examples and fragments of a species, which is with- 

 out doubt identical with the one named above, were found in bed No. 3 

 of the Crow Creek section. The species, which is the type of tlie sub- 

 genus Leptesthes^ was originallj^ discovered in the upper part of the 

 Bitter Creels series, near Black Buttes Station, Wyoming. It has been 

 found there quite abundantly where it is quite variable in form, and 

 Avhere it also reaches a larger size than the average at the other localities 

 at which it has been discovered. It is kuo^vn at other localities w^est 

 of the Eocky Mountains, and was also obtained by Dr. Hayden from 

 the same shaft with Nos. 1 and 13, two hundred miles east of Denver, 

 Colo. 



No. 12. Corhicula (Leptesthes) niacropistha White. 



The type-specimens of this species came from No. 3 of the Crow Creek 

 section, but it was also obtained in the valley of Bijou Creek, and 

 at these two localities only. It is the smallest known sjiecies of this 

 subgenus, in which respect it contrasts strongly with the type-si)ecies 

 of Leptesthes, noticed in the last paragraph. It is described in the Bul- 

 letin of the Geological and Geographical Survey of the Territories, 

 vol. iv, p. 713. 



No. 13. Corhicula, {Leptesthes) planumhona Meek. 



This species was obtained in considerable numbers from be<l No. 3 of 

 the Crow Creek section, and also, but less plentifully, in tlie valley of 

 Bijou Creek. It was originally discovered " two hundi-ed miles east of 

 Denver City, on the Kansas Pacific Riiilroad, where they were found in 

 a shaft at a depth of 40 feet below the surface." By reference to 



