42 PALEONTOLOGY OF THE EUEEKA DISTEICT. 



width more than one-half the length of the limb between it and the glabella, 

 somewhat flattened and with a narrow groove between it and the depressed 

 limb; posterior lateral limbs narrow, marked by the extension of the occip- 

 ital furrow within their posterior margin. The facial sutures cut the 

 frontal rim obliquely, and recurving inward pass to the palpebral lobes; 

 curving around these opposite the central portion of the glabella, they then 

 extend obliquely outward and backward, cutting the posterior margin 

 beyond a line with the eyelobes. 



Surface smooth to the unaided eye ; minutely punctate under a strong 

 magnifying power. 



This species is distinguished by its broad fixed cheeks and long frontal 

 margin with the flattened rim. 



Formation and locality. Cambrian. Prospect Mountain Group, upper 

 beds of the Secret Canon shale, on the opposite side of the cafion from the 

 dump of the shaft of the Richmond mine, Ruby Hill, Eureka District, 

 Nevada. 



Dicellocephalus f angustifrons, n. sp. 

 Plate x, figs. 1, la ft. 



Glabella subquadrate; width at the base equal to the length, but nearly 

 one-third greater than the width of the anterior margin ; surface moderately 

 convex, curving down in front and marked by two pairs of lightl}- impressed 

 glabellar furrows that extend obliquely inward one-third the distance across 

 the glabella, the posterior pair nearly separating the posterior triangular 

 lobes; occipital ring rather broad and distinctly defined by a strong occip- 

 ital furrow; dorsal furrows narrow but strongly impressed; fixed cheeks 

 very narrow and hardly Separable from the palpebral lobes, which are large, 

 elongate, and situated opposite the central portion of the glabella; frontal 

 limb merely a line between the glabella and the rounded rim; lateral limbs 

 only partly known; they appear to be narrow and rather short. 



Associated with the glabella and fixed cheeks are numerous free cheeks 

 that undoubtedly belong to this species. They are triangular with the 

 upper angle truncated to form the base of the eyelobe; the outer margin 

 is strong, somewhat flattened, and separated from the rapidly ascending 

 slope to the furrow at the base of the eye by a sharp narrow groove. The 



