28 PALEONTOLOGY OF THE EUKEKA DISTKICT. 



Agnostus prolongus H. & W. 



Agnostus prolongus Hall & Wkitfield, 1877. Geol. Expl. Fortieth Parallel, vol. iv, 

 p. 230, pi. 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 Canon, 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. 



