FOSSILS OF THE CAMBRIAN. 29 
Olenellus Gilberti Meek. 
Plate ix, fig. 16, 16a; pl. xxi, fig. 13. 
Olenellus Gilberti Meek, 1874. (Manuscript.) 
Olenellus Gilberti White, 1874. Geog. and Geol. Expl. and Surv. West 100th Merid.; 
Prelim. Rep. Invert. Foss., 7. 
Olenus (Olenellus) Gilberti Meek, 1875. Geog. and Geol. Surv. West 100th Merid., vol. 
ili, Geology, p. 182. 
Olenellus Gilberti White, 1875. Geog. and Geol. Expl. and Surv. West 100th Merid., 
vol. iv, pt. i, p. 44, pl. li, figs. 3 a, e. 
Head semioval in outline, moderately convex, margined all around by 
_a narrow wire-like rim, which is produced at the genal angles into slender 
spines Glabella elongate, narrowing slightly towards the front; general 
surface moderately convex anteriorly, becoming less so back of the frontal 
lobe; the glabellar furrows penetrate obliquely backward nearly to the 
median line, with the exception of the second anterior pair, which are 
shown by elongate depressions on the line of division of the second and 
third anterior lobes, the two lobes uniting laterally so that the furrows do 
not extend to the dorsal furrows; the frontal glabellar lobe is convex, oval 
in outline, with a tendency in some examples to become angular in front; 
the two posterior lobes are subequal in size; the occipital ring and furrow 
well defined; eyes elongate, narrow, arching outward from the point where 
the anterior glabellar furrow meets the dorsal furrow, and backward 
to the posterior glabellar furrow; dorsal furrows shallow; the fixed and 
free cheeks united form a broad slope from the eye to the lateral margins 
and anteriorly merge into the long frontal limb. The facial sutures cannot 
be traced in any of the specimens. Thorax and pygidium unknown. | 
The above description is drawn from specimens obtained in the Eureka 
District. The differences between them and the type specimens are almost 
entirely in the frontal limb, the former having a much broader space between 
the front of the glabella and marginal rim. In some examples from the 
typical locality of the species at Pioche, Nevada, the frontal limb is much 
broader than in those illustrated in Dr. White’s report, the Eureka form 
appearing to be specifically identical with them. 
Formation and. locality—Cambrian. Prospect Mountain Group, in an 
arenaceous shale above the quartzite capping Prospect Peak, Eureka Dis- 
trict, Nevada. 
