28 PALEONTOLOGY OF THE EUREKA DISTRICT. 
Agnostus prolongus H. & W. 
Agnostus prolongus Hall & Whitfield, 1877. Geol. Exp]. Fortieth Parallel, vol. iv, 
p. 230, pl. i, figs. 30, 31. 
This form was originally collected in the Eureka District, but it is 
rare, having been found only in the Hamburg belt of limestone northeast 
of Adams Hill, and on the west side of Sierra Cation, Eureka District, Ne- 
vada. 
Genus OLENELLUS Hall. 
Olenellus Iddingsi, n. sp. 
Plate ix, fig. 12. 
General outline of the head roughly subtriangular, with the length 
one-half the breadth of the posterior border; strongly convex; the rather 
narrow, rounded rim bordering the anterior margin suddenly becomes 
thickened and rounded opposite the eyes and is extended back in the short, 
strong, slightly curved genal spines, the narrow posterior marginal border 
uniting with it at the genal angles. Glabella elongate, narrow, divided by 
four transverse furrows into five lobes; the anterior is round, tumid, and ex- 
panded laterally, while the four posterior are narrow, transverse, of equal 
size, and with their sides parallel; occipital ring and furrow not recog- 
nized; eyes lunate, situated opposite the central lobes of the glabella. 
Facial suture in front of the eye unknown; back of the eye it extends 
obliquely outward and backward, cutting the posterior margin about two- 
thirds the distance from the glabella to the postero-lateral spine. 
Thorax and pygidium unknown. 
The specific name is given in honor of Mr. J. P. Iddings, the discov- 
erer of the type specimen. 
Formation and locality—Cambrian. Prospect Mountain Group, in an 
arenaceous shale above the quartzite capping Prospect Peak, Eureka Dis- 
trict, Nevada. 
