WHITE.] LARAMIE FOSSILS OF BITTER CREEK VALLEY. 221 



tlie Laramie Group. Mr. ]Meek obtained his type specimens at tlie Black 

 Biittes locality, and it lias since been obtained in considerable numbers 

 both east and west of the Eocky Mountains, in Colorado and Wyoming-, 

 but it has not yet been discovered in the Upper Missouri Eiver region. 

 Its wide geographical distribution ; its great vertical range in the Lara- 

 mie Group ; its apparently true Melanian tyi)e and its relation to the fol- 

 lowing' species from a lower horizon in the group in Bitter Creek Valley, 

 all make it a species of unusual interest. For fiu-ther remarks on it 

 see notes on Laramie fossils from Crow Creek Valley and the Dauforth 

 Hills localities. 



26. Mclania inscnlpta Meek. 



Mr. Meek described this species in the Ann. Eeport of the U. S. Geol. 

 and Geog. Sm\ Terr, for 1872, p. 515, along with 31. ivTjomingcnsis, his 

 types of the former ha-^ing- been obtained at Eock Springs, and those of 

 tiie latter at Black Buttes Station. No examples of M. insculpta have 

 been found elsewhere than at Eock Springs, except two or three imper- 

 fect ones at the locality two miles below Point of Eocks. It is much 

 more nearly related to M. injomiiujcnsis than woidd appear at first glance, 

 because the principal difference consists in the row of i^rominent nodes 

 or short spines that adorn the larger volutions of the latter ; while the 

 upper turns of the spine of each seem to be undistinguishable. This is 

 a u other case of very closely related species or well-marked varieties 

 existing the one above and the other below the line of unconformity that 

 has been shoA^Ti to exist in the Laramie strata of Bitter Creek VaUey. 



27. Viviparus plicapressus White. 



The only localities at which this species has yet been discovered are 

 those of Black Buttes Station and Yampa Valley. At the latter locality 

 it was found associated with Melania wyomingensis and N'eritina volvili- 

 neata ; and at the former with Unio, Corhula^ Goniohasis, Cassiopellay 

 Ckimr>cloma, &c. It is described in Powell's Eeport on the Geology of the 

 Uinfa Mountains, p. 133. It is not yet known east of the Eocky Mount- 

 ains. 



28. Tulotoma thompsoni White. 



Black Buttes Station is the first locality at which this species was dis- 

 covered, and the valley of Crow Creek, east of the moimtains, is the only 

 other one at which it has been found. It occurs in considerable numbeis 

 at each of these localities, and its identity at each is beyond question. 

 Its associates at Crow Creek are all fi'esh-water forms ; and at Black 

 Buttes it seems to occupy a thin layer by itself between those wliich con- 

 tain both brackish- and fresh-water forms. See further remarks luider 

 the head of "Notes on the Laramie fossUs of Crow Creek VaUey." 



29. Campeloma vetula Meek & Hayden. 



Dr. Hayden first discovered this species in the Judith Eiver beds of 

 the Upper Missouri Eiver region, and it is described and figTu?ed in volume 

 IX of the United States Geological Sm-vey of the Territories. A goodly 

 number of examples were obtained at Black Buttes Station, where they 

 were found associated -svith Unio, CorhuJa, Goniohasis, CassiopcUa, &c. 

 Their specific identity with Campeloma vetula seems to be unmistakable. 



30. Campeloma multistriata Meek & Hayden. 



Some examples found associated with the foregoing; species at Black 

 Buttes Station possess distinct revohing lines like those of C. multistriata, 

 but they lack the shouldering of the distal side of the body-volution so 

 common in that species. As they do not appear to differ materially in 



