30 PALEONTOLOGY OF THE EUREKA DISTRICT. 



Olenellus Howelli Meek. 

 Plate ix, figs. 15, 15 a, b, and pi. xxi, figs. 1, 9. 



Olenellus Howelli Meek, 1874. (Manuscript.) 



Olenellus Howelli White. 1874. Geog. and Geol. Expl. and Surv. West 100th Merid. ; 



Prelim. Rep. Invert. Foss., p. 8. 

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



iii, Geology, p. 183. 

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



vol. iv, pt. 1, p. 47, pi. ii, figs. 4 a, b. 



The general outline of the head of the adult is semi-elliptical or semi- 

 circular and more or less strongly convex. The margin is bordered by a 

 narrow, rounded rim which becomes thickened near the genal angles and 

 continues posteriorly as rather short, sharp spines. The glabella is elon- 

 gate and more or less expanded in front and behind, contracting a little 

 midway ; four pairs of glabellar furrows penetrate from each side ; they are 

 somewhat strongly impressed on each lateral third of the width of the gla- 

 bella, becoming more shallow as they pass into the more shallow furrow that 

 unites them across the center; in younger specimens this furrow is undis- 

 tinguishable from the lateral furrows and they all unite as one distinct fur- 

 row crossing the glabella from side to side, and even in the adults this fea- 

 ture is strongly marked in some individuals; the anterior lobe of the gla- 

 bella is more or less tumid, subhemispherical or a little transverse and wider 

 than the greatest width of the glabella immediately behind it; the next pos- 

 terior lobe is rather narrow and transverse, differing from the two next pos- 

 terior lobes, which arer wider and curved a little forward at the ends, by the 

 direction of the furrows ; the posterior lobe corresponding to the occipital 

 ring or segment is broad and essentially of the same character as that pre- 

 ceding it; the furrow separating them is very shallow at the center and in- 

 clined obliquely backward at the sides; a small node occurs on one example 

 at the center of the occipital ring. 



Eyes elongate, narrow, and arching from opposite the anterior glabellar 

 lobe to opposite the occipital furrow. The dorsal furrows are narrow, dis- 

 tinctly but not deeply impressed. Fixed cheeks a little expanded anteriorly 

 and scarcely more than a line between the elongate palpebral lobes and the 

 dorsal furrows, while posteriorly they merge into the small triangular late- 

 ral limbs; frontal limb obsolete. Free cheeks large, roughly subtriangular 



