FOSSILS OF THE LOWER SILURIAN. 



93 



congeneric, but whether belonging to this genus or not it is difficult to deter- 

 mine in the absence of the thorax and pygidium. 



Formation and localities. Pogonip Group, on spur southwest of Wood 

 Cone and below Bellevue Peak, Fish Creek Mountains, Eureka District, 

 Nevada. 



Bathyurus ? simillimus, n. sp. 

 Plate xii, fig. 11. 



This species is closely related to the preceding and to B. oblongus 

 Billings, (Joe. cit. p. 92) in the form and convexity of the glabella and fixed 

 cheeks; the frontal limb, however, is longer, curved more abruptly down- 

 ward, and bordered by a rounded rim that has a distinct, very obtuse angu- 

 larity in front. 



The surface of the glabella is minutely granulose. 



Formation and locality. In the limestone of the Pogonip Group, on the 

 north slope of White Mountain, about 500 feet from the summit of the 

 mountain, Eureka District, Nevada. 



The pygidium, illustrated by fig. 14 of plate xii, is of the same type as 

 that upon which Mr. Billings founded the species Bathyurus caudatus (Pal. 

 Foss., vol. i., p. 261, fig. 245, 1865), which occurs in the Quebec Group of 

 Newfoundland. It undoubtedly belongs to a distinct species; its generic 

 relations are not recognized. 



Genus CYPHASPIS Burmeister. 



Cyphaspis ? brevimarginatus, n. sp. 

 Plate xii, fig. 10. 



Glabella conical, strongly convex, marked by a pair of posterior gla- 

 bellar furrows extending obliquely inward so as to nearly separate a small 

 lobe at each postero- lateral angle ; occipital segment broadest at the center 

 narrowing towards the dorsal furrows; occipital furrow well defined; dorsal 

 furrows distinctly impressed along the sides of the glabella; fixed cheeks 

 rather narrow midway, widening in front; frontal limb as a scarcely per- 



