FOSSILS OF THE POTSDAM GKOUP. 215 



This species approaches more nearly to ConocepJialites Slmmardi Hall 

 (16th Eept. State Cab., p. 154, pi. 1, fig. 7, and pi. 8, fig. 2) than to any 

 other described species, but differs very conspicuously in the greater breadth 

 of the front of the head between the facial sutures. No other parts of the 

 organism have been detected. Although the fragments of rock containing 

 the heads are filled with Trilobitic remains, there are none showing the ■ 

 granulose surface corresponding to this one ; and, where the entire crust of 

 the head is so thickly covered with granules, it would seem natural to sup- 

 pose the other parts of the animal would be similarly marked. 



Formation and locality. — In compact limestone of the Potsdam group at 

 Eureka, Nevada. Collected by J, E. Clayton, esq. 



Crepicephalus (Loganellus) maculosus n. sp, 



Plate II, figs. 24, 25, and 26?. 



Glabella and fixed cheeks quadrangular; glabella rounded, conical, a little 

 higher than wide, and highly convex, prominent and gibbous along the 

 median line, marked by very oblique furrows, only two pairs of which show 

 upon the cast, except on critical examination, the anterior pair being very 

 obscure, and situated very near the anterior end of the glabella ; middle 

 pair more distinct, and situated at about the anterior third of the length ; 

 posterior pair commencing a little behind the middle of the length, at the 

 margin, and directed backward so as to unite with the occipital furrow just 

 before reaching the center of the glabella, separating the posterior glabel- 

 la,r lobes, which form triangular areas of large size; occipital furrow wide, 

 and ring distinct 



Fixed cheeks nearly half as wide as the central diameter of the glabella, 

 moderately prominent in the middle near the eye-lobe, and gently declining 

 in front and posteriorly ; ocular ridges stronglj^ marked. Frontal limb 

 longer than the width of the fixed cheeks, strongly convex in front of the 

 glabella, and rapidly declining to the front margin, Avhich has been bordered 

 by a narrow rim, the form and extent of which has not been determined. 

 Lateral limbs unknown. Surface of the cast, except the glabella, which is 

 smooth, marked by distant elevated pustules of moderate size. 



A movable cheek, associated in the same blocks, and possessing a simi- 



