56 GEOLOGICAL SURVEY OF THE TERRIEORIES. 
from the Cation of Desolation, Green River, Utah, by Professor Powell; 
the strata there being evidently equivalent with those at Wales. 
Omitting special consideration of the fossils of the foregoing brief lists, 
although they are believed to really belong to the Laramie Group, the 
plan of the remainder of this article will embrace an enumeration of all 
the well-ascertained invertebrate species of the Laramie Group, inelud- 
ing those of the Bear River series. Full descriptions, however, are 
given in this article of those species only which are illustrated upon the 
accompanying plates. For the purpose, however, of giving a’ full ex- 
hibit of the well-recognized molluscan fauna of the Laramie Group, the 
names of all the other species are given in systematic order, with vefer- 
ences under each to the work or works in which descriptions and illus- 
trations of them may be found. ‘This article will thus present a synop- 
sis of the invertebrate fauna of the Laramie Group, as it is known at 
the present time. It is a conspicuous fact that the invertebrate fauna 
thus presented consists wholly of mollusca. The only known examples 
ot forms which do not belong to this class, that have been found in this 
group, are a few small Ostracoid Crustaceans, and some egg-masses of 
an insect described by Mr. Scudder under the name Corydalites fecundum, 
in 1878, in Bull. U.S. Geol. Sur. Terr., vol. iv, pp. 537-540.* — 
Besides the described species herein enumerated, there are known frag- 
ments of some others which are too imperfect for specific description ; 
and in view of the fact that every season’s examination of the strata of 
this great group in the field has brought to light new forms, we may 
safely conclude that many more will yet be added to the already inter- 
esting and important invertebrate fauna of the Laramie Group. 
CONCHIFERA. 
Genus OSTREA Linneeus. 
OSTREA GLABRA Meek & Hayden. 
Ostrea glabra Meek & Hayden (1857), 1876, vol. ix, U. S. Geol. Sur. Terr. (4to ser.), 
p. 509, plate 40, figs. 2, a, b, c, and d. 
Ostrea wyomingensis Meek, 1873, An. Rep. U. 8. Geol. Sur. Terr. for 1872, p. 508. Illus- 
trated on plate 20 of this article. 
Osirea arcuatilis Meek, 1873, An. Rep. U. S. Geol. Sur. Terr. for 1872, p. 477. 
Ostrea insecuris White, 1876, Powell’s Rep. Geol. Uinta Mts., p. 112. Illustrated on 
plate 21 of this article. 
Compare Ostrea subtrigonalis Evans & Shumard, 1857 (redeseribed and illustrated by 
Meek), vol. ix, U. S. Geol. Sur. Terr. (4to ser.), p. 510, pl. 40, figs. 1, a, b, ¢, 
and d. 
By the foregoing synonymy it will be seen that I refer all the forms 
of Ostera yet described from the Laramie Group to one and the same 
species, except, perhaps, O. subtrigonalis, the reasons for which may be 
found stated upon pages 162, 208, and 217 of the report of this survey 
for 1877. The first and fifth forms are figured by Meek in vol. ix, pl. 40, 
U.S. Geol. Sur. (4to ser.). The second and fourth forms are illustrated 
on plates 20 and 21, which accompany this article, but the third is not 
vet illustrated. It is plainly only a variety of the variety O. wyomingen- 
sis, with typical forms of which it is associated. 
A small Ostrea oceurs not unfrequently in the Bear River Laramie 
series, which is probably a distinct species, but no examples sufficiently 
characteristic have yet been obtained. 
* These interesting objects will be discussed by Mr. Scudder in his forthcoming work, 
Tertiary Insects of North America, and figured on plate 4, accompanying that work, 
figs. 4-7, 13-16, 18-21, and 23. 
