white] ANNOTATED CATALOGUE. 61 



Laramie beds of Southwestern Wyoming and the adjacent parts of 

 Utah, which 1 described uDder the name of Viviparus couesii* it is 

 represented on Plate 8. 



The only species of Viviparus that is yet known to occur in the Judith 

 Elver beds of the Upper Missouri 'River region is V. eonradi Meek «.\: 

 Hayden,f which is illustrated on Plate 24; but the genus is abun- 

 dantly represented in the Fort Union beds. Six species and one variety 

 have been described by Meek & Hayden from the latter beds, under 

 the following names (figures of which are given on Plates 24, 25, and 27) : 

 Viviparus peculiaris, V. trochiformis, V. leidyi, V. leidyi. var. formosa, 

 Y. reynoldsianus, V. leai and Y. retusus.% A glance at these illustra- 

 tions will show that the species they represent are evidently allied to 

 each other, the relationship being so close in some cases as to suggest 

 that future discoveries of specimens will probably reveal intermediate 

 forms that must reduce the number of recognizable species by one-half 

 at least. 



A form similar to but shorter and more compact than Viviparus leai 

 has been obtained from the Laramie strata of Crow Creek Valley east 

 of the Rocky Mountains in Colorado, which is figured on Plate 25, and 

 which I have described under the name of Viviparus prudentius.§ 



From certain strata in Central Utah, probably belonging to the 

 Laramie Group, Professor Powell obtained some forms of Viviparus 

 which closely resemble V. trochiformis and V. leidyi, respectively, and 

 with which they are probably identical. 



At Black Buttes Station, in Southern Wyoming, Viviparus plica- 

 pressus\\ White, together with numerous other fresh and brackish water 

 forms, have been tbund in the Laramie strata there, most of which have 

 been mentioned on previous pages. This species is represented on 

 Plate 24. 



Another form, somewhat similar to V. trochiformis, to which I gave 

 the name of V. panguitchensis,^] was obtained by Professor Powell from 

 strata in Southern Utah, which, doubtless, belong to the Laramie Group. 

 It is figured on Plate 25. 



One of the most interesting species that has as yet been obtained 

 from the Laramie Group is Tulotoma thompsoni** White, which has been 

 found in Southern Wyoming, west of the Rocky Mountains, and also 

 east of the same in Colorado. It is illustrated on Plate 24. It is 

 referred to the genus Tulotoma Haldeman, rather than to Viviparus, 

 because of its nodular ornamentation; but since the operculum has 



*Au. Eep. U. S. Geol. Sur. Terr, for 1878, Part I, p. 99, pi. 30, fig. 1. 

 tU. S. Geol. Sur. Ter., vol. ix, p. 579, pi. 42, fig. 15. 



J: For descriptions and figures of all these forms, see U. S. Geol. Sur. Terr, vol. ix, 

 pp. 577-584, pi. 44. 



§An. Eep. U. S. Geol. Sur. Terr, for 1878, Part I, p. 98, pi. 28, fig. 5. 

 l| An. Eep. U. S. Geol. Sur. Terr, for 1878, Part I, p. 98, pi. 28, fig. 6. 

 If Powell's Rep. Geology Uinta Mountains, p. 123. 

 **An. Eep. U. S. Geol. Sur. Terr for L878, Part I, p. 100, pi. 28, fig. 2. 



