white.] ANNOTATED CATALOGUE. 57 



have been found in any other strata of the Laramie Group except those 

 which are strictly equivalent with those beds. 



One other species, which I have described under the name of Gonio- 

 basis endlichi,* is found associated with the four species that have just 

 been mentioned. It is represented on Plate 6. This form belongs to 

 another type, which includes G. nebrascensis, presently to be men- 

 tioned, and which, as before suggested, probably belongs near Lioplax 

 Troschel. 



Five species were described by Meek & Hayden from the Judith Eiver 

 Laramie beds of the Upper Missouri Eiver region, under the generic 

 name of Goniobasis, namely, G. convexa, G. invenusta, G. sublcevis, G. 

 omitla, and G. ? subtortuosa,] all of which are represented on Plates, 

 26 and 27. It seems probable that G. sublcevis and G. invenusta are 

 only varieties of G. convexa,. G. omitta is much like G. gracilenta from 

 the Fort Union beds, presently to be mentioned; but O.f subtortuosa 

 is quite different from any other form that has been referred to Gonio- 

 basis. It probably belongs to some other genus, perhaps to Gassiopella 

 White, which will be further mentioned on a following page, but that 

 question cannot yet be determined because the characters of the base 

 and aperture of the former are not yet knowD. 



From the Fort Union Laramie beds of the Upper Missouri River re- 

 gion three species have been described by Meek & Hayden, namely, 

 Goniobasis gracilenta, G. nebrascensis, and G. tenuicarinata.% The two 

 latter species have already been referred to as representing a separate 

 section of the genus Goniobasis, if, indeed, they belong to that genus. 

 They are represented on Plate 26. Both species have also been recog- 

 nized in the coal-bearing strata at the town of Wales, Utah, and G. 

 tenuicarinata has been found in the Laramie strata of Crow Creek 

 Valley in Northern Colorado, east of the Eocky Mountains. At the last- 

 mentioned locality, as well as at Black Buttes Station in Southern Wyo- 

 ming, Goniobasis gracilenta has been recognized. The species is repre- 

 sented on Plate 26. 



It will thus be seen that thirteen species in all have been described 

 and referred to Goniobasis from the Laramie (iroup alone. Even in 

 case several of the specific names that have been applied to these forms 

 should, as already suggested, prove to be merely synonyms, still it is 

 clear that in the great Laramie Group there is a goodly number of well- 

 defined species of Goniobasis, as that genus is now understood. 



From the Laramie strata at Black Buttes Station, which have been 

 so often mentioned, several specimens of a shell have been obtained, to 



* An. Rep. U. S. Geol. Snr. Terr, for 1878, Part I, p. 92, pi. 30, fig. 7. 



tEor descriptions and figures of these five species, seeU. S. Geol. Sur. Terr., vol. ix, 

 pp. 562-570, pi. 42. 



t For descriptions and figures of these three species, see U. S. Geol. Sur. Terr., vol. ix, 

 pp. 5G5-568, plates 42 and 43. 



