FOSSILS OF THE CAMBRIAN. 29 



Olenellus Gilbert! Meek. 

 Plate ix, fig. 10, 16 a; pi. xxi, fig. 13. 



Olenellus Gilberti Meek, 1874. (Manuscript.) 



Olenellus Gilberti White, 1874. Geog. and Geol. Expl. and Surv. West lOOtb Merid.; 



Preliin. Rep. Invert. Foss., 7. 

 Olenus (Olenellus) Gilberti Meek, 1875. Geog. and Geol. Surv. West 100th Merid., vol. 



iii, Geology, p. 182. 

 Olenellus Gilberti White, 1875. Geog. and Geol. Expl. and Surv. West 100th Merid., 



vol. iv, pt. i, p. 44, pi. ii, 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 denned; 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 loctdity. Cambrian. Prospect Mountain Group, in an 

 arenaceous shale above the quartzite capping Prospect Peak, Eureka Dis- 

 trict, Nevada. 



