CONTRIBUTIONS TO INVERTEBRATE PALEONTOLOGY NO. 7; JU- 
RASSIC FOSSILS FROM THE WESTERN TERRITORIES, 
By ©. A. WHITE, M: D. 
The fossils embraced in this article have been collected by different 
persons who have been connected with the various government surveys 
in the western portion of the national domain. Six of the species are 
here described for the first time, and two of them were described by the 
writer in Professor Powell’s Report on the Geology of the Uinta Mount- 
ains. The remainder were named by the late Mr. Meek in a catalogue 
of fossils which he published in the annual report of this survey for 1872. 
The brief characterization which he there gave of them in the form of 
foot-notes is insufficient for their identification, but the type-specimens 
have all been recognized by means of the registered numbers which they 
bear in the records of the National Museum, and his names are therefore 
retained. 
The specimens have all been reported as from the Jurassic by those 
who collected them. All but two of the species are believed to be from 
strata of unquestionable Jurassic age. These two, Aviculopecten super- 
strictus and Volsella (Modiolina) platynota, are possibly from the horizon 
of the Triassic fossils which form the basis of Contributions to Inverte- 
brate Paleontology No. 5, already given on preceeding pages. The 
reasons for entertaining this opinion are presented in connection with 
the description on following pages of the two species named. 
Genus CAMPTONECTES (Agassiz) Meek. 
CAMPTONECTES PLATESSIFORMIS White. 
Plate 37, fig. 5 a. 
Camptonectes platessiformis White, 1876, Powell’s Rep. Geol. Uinta Mts., p. 93. 
Camptonectes cxtenuatus Whittield, 1877 (not Meek & Hayden), Prelim. Rep. Paleont. 
Black Hills, p. 47. 
Shell, exclusive of the ears, subelliptic in marginal outline, the height 
being considerably greater than the width; the whole border below the 
ears forming a continuous and almost true elliptic curve; hinge line 
moderately long. Left valve gently convex; the ears moderately large, 
nearly rectangular, subequal, the anterior one perhaps slightly larger 
and a little more prominent than the other, defined from the body of the 
shell by their flattening.and not by distinct auricular furrows; umbonal 
portion of the valve well defined by its straightened sides converging 
to the beak, which is small and projects little, if any, beyond the car- 
dinal border. Surface marked by numerous comparatively coarse, radi- 
ating, crenulated, raised lines, which, near the base, begin to be curved 
outward to the margins, the curvature of the lines increasing towards 
143 
