FOSSILS OF THE CAMBRIAN. 



49 



Ptychoparia (Solenopleura?) breviceps, n. sp. 

 Plate x, fig. 9. 



Head rather small, convex, semicircular; length a little less than one- 

 half the width of the posterior margin. Glabella large, prominent; length 

 and width at the base nearly equal, converging rapidly towards the trun- 

 cated front to three-fifths the width of the base; the posterior glabellar 

 furrow extends entirely across, while the two anterior pairs are scarcely 

 discernible; occipital ring transverse, rounded, separated from the glabella 

 by a strong, rounded furrow, and extending laterally as the narrow rounded 

 posterior border of the head ; dorsal furrows strongly defined ; fixed cheeks 

 convex, depressed below the level of the glabella, rather wide and sloping 

 abruptly to the frontal border, slightly depressed towards the small palpe- 

 bral lobes and sloping away rapidly posteriorly; ocular ridges strongly 

 marked, trending obliquely backward from the antero-lateral angles of the 

 glabella; postero-lateral limbs rather narrow, distinctly grooved on the 

 posterior edges by the occipital furrows; frontal limb obsolete, the strong, 

 rounded, marginal border touching the anterior margin of the glabella. 

 Facial suture curves slightly inward in its course from the eyelobe to the 

 front margin of the head, and apparently cuts obliquely inward across the 

 frontal rim ; behind the eye it is directed outward, curving a little backward 

 to the posterior margin and outlining an elongate triangular lateral limb. 



Surface apparently smooth or very finely punctate. 



Formation and locality. Cambrian. Prospect Mountain Group, in the 

 Hamburg shale belt north of Adams Hill, Eureka District, Nevada. 



Ptychoparia (?) pernasutus, n. sp. 

 Plate x, figs. 8, 8 a-b. 



Entire form unknown. The glabella and fixed cheeks, and the free 

 cheeks associated with them, give the head a rounded, subtriangular form; 

 it is strongly convex and produced anteriorly in a strong, elongate, flattened 

 triangular process, the anterior third of which bends downward with a uni- 

 form curvature; the width of the process at the base is about two-thirds of 

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