FOSSILS OF THE CAMBRIAN. 



43 



union of the free cheeks with the fixed cheeks would give the head a semicir- 

 cular, strongly convex form, with rounded postero-lateral angles. The 

 pygidium occurring with the other parts is transversely elliptical, about 

 one-third wider than long, and elevated on the median lobe; the frontal 

 margin is broadly rounded, the lateral margins scarcely angular at the 

 union of the frontal margin and the more sharply rounded posterior line; 

 axial lobe elevated, convex, about one-half the length of the pygidium, and 

 marked by six transverse rings, including the terminal one; lateral lobes 

 broad, sloping rapidly away from the axial lobe and then spreading out in 

 a broad, flattened border; their surface is marked by three broad anchy- 

 losed segments, besides the narrow anterior articulating projection and the 

 broad posterior termination. 



Surface of the head finely granulose, and the pygidium the same, with 

 the exception of the irregular striae on the border, the latter are sub- 

 parallel to the margin. 



This species in the general form of the head and pygidium resembles 

 many species referred by Mr. Billings to his genus Bathyurus, but it. is 

 nearer Dicellocephalus, if we compare it with typical forms of the genus 

 from the Potsdam sandstone of Wisconsin, and is referred to that genus 

 provisionally. 



Formation and localities. Cambrian. Prospect Mountain Group. 

 Summit of Hamburg shale, on the ridge north of the Dunderberg mine, 

 and in a matrix of a similar character at the southeast base of Lookout 

 Mountain, Sierra Canon, Eureka District, Nevada. 



Dicellocephalus lole, n. sp. 

 Plate x, fig. 19. 



Glabella subquadrate, length exclusive of the occipital ring equal to 

 the width at the base; it narrows a trifle anteriorly, is transverse in front, 

 and has its lateral angles rounded; surface gently convex, rounding down- 

 ward in front, and marked by two pairs of rather strong, but not deeply 

 impressed, furrows that extend obliquely inward well towards the median 

 line. 



