WHITE.] ANNOTATED CATALOGUE. 437 



we find in Southwestern Wyoming, and the adjacent parts of Utah, one 

 species of Corbicula which is interesting as being the type of a section 

 of that genus for which Mr. Meek proposed the subgeneric name of Ve- 

 loritina* This species, which he described under the name of Corbic- 

 ula ( Veloritina) durlceei, t is represented on Plate 8. 



Two species of Corbicula were described by Meek & Hayden from the 

 Judith Eiver beds of the Upper Missouri Eiver region, under the names 

 respectively of C. cyihtriformis and C. occidentalism which are repre- 

 sented on Plates 22 and 23 respectively. The first-named species is 

 referred to the typical section of the genus ; but the latter approaches 

 -in form the type of the subgenus Veloritina. Both these species have 

 also been obtained from Laramie strata of Bitter Creek Valley in 

 Southern Wyoming. 



The form which was described by Meek from that region, under the 

 name of C. bannister i, is regarded as identical with C. occidentalis.l This 

 form is represented on Plate 17. 



Two other Laramie species of Corbicula were described by Meek & 

 Hayden, from the Upper Missouri Eiver region, both of which are, how- 

 ever, from the Fort Union beds. They are respectively C. nebrascensis 

 and C. subelliptica, both of which are represented on Plate 20. The 

 latter has been recognized in the Laramie strata of Colorado east of the 

 Eocky Mountains. It was referred by Mr. Meek to his subgenus Lep- 

 testhes.\\ 



It seems not improbable that C. nebrascensis is only a young example 

 of C. cytheriformis, but as that question is not yet settled, the former is 

 here treated as a distinct species as well as the latter. 



The Laramie strata east of the Eocky Mountains in Colorado, which 

 were by Dr. Hayden designated as the Lignitic Group, have been found 

 in several localities to be especially rich in Corbicula. A part of these 

 species are referable to the typical section of the genus and a part to 

 the subgenus Leptesthes. To the latter subgenus belong C. subelliptica 

 Meek & Hayden, C. macropistha White, C. planumbona Meek, and C. 

 cardiniceformis White ; fl all of which are figured on Plates 21 and 22. 



Since the last-named form was published numerous other examples 

 have been discovered which make it probable that it should be regarded 

 as a variety of C. fracta Meek. 



Other published species found in the valley of South Platte, and its 

 tributaries in Colorado, are C. cleburni and 0. obesa White,** which are 

 figured on Plates 20 and 23 respectively. 



*See U. S. Geol. Sur. Terr., Vol. ix, p. 161, for a diagnosis of this subgenus. 



tU. S. Geol. Sur. 40th parallel, vol. iv, p. 167, pi. Ivi, fig. 6. 



t U. S. Geol. Terr., vol. ix, pp.520, 521, pi. 40, figs. 5 aud 6. Also, An. Rep. U.S. 

 Geol. Sur. Terr, for 1878, Part I ; pp. 74, 75, pi. 21. 



$ See An. Rep. U. S. Geol. Sur. Ter. for 1878, Part I, p. 75. 



|| For diagnosis of this subgenus, see U. S. Geol. Sur. Terr., vol. ix., p. 161. 



IF These species are described an.d figured in the An. Rep. U. S. Geol. Sur. Terr, for 

 1878, Part I. References are also given there to original descriptions. 



** See An. Rep. U. S. Geol. Sur. Terr, for 1878, part I, pp. 73, 73, pi. 23. 



