40 PlilMOKDlAL PEKIOD. 



This beautiful Agnostus is quite unlike any described American species, 

 and is more nearly related to A. integer Beyricli, from the Primordial strata 

 of Europe, than any otlier known to me. Compared with that species, it is 

 found to reach a larger size ; its glabella is narrowed in front instead of 

 having its sides nearly parallel ; the axial lobe of the pygidium is nar- 

 rower behind than in front, instead of being of nearly the same width at 

 each end, and has the sides of that lobe convex instead of nearly straight, as 

 they are in A. integer. 



Position and locality. — Shales of the Primordial period, probably of the 

 Potsdam epoch, Antelope Spring, House range, Utah, where it is associated 

 with Conocoryphe Kingii Meek, and other fossils of Primordial type, and 

 where three entire specimens have been obtained, besides a number of 

 fragments. 



Family CONOCORYPHID^. 



Genus OONOGORYPHE Cortla, 1847. 

 Subgenus PTYCHOPARIA Coicla, 1847. " 

 Conocoryphe (Ptychoparia) Kingii Meek. 



Pliite II, lig, 2 a, I), and c. 



Conocorijphe {ConocepJialites) Kingii Meek, 1870, Proc. Acad. Nat. Sci. Phila., 63, 

 Conocoryphe [Ptychoparia) Kingii Meek, 1872, Geol. Surv. Montana, Idaho, Wyoming, 

 & Utah, 487. 



Outline of bod}^ ovate ; the width compared tfith the length being 

 about as two to three. Head semicircular, or nearly so ; the exterior margin 

 regularly rounded, and bordered by a narrow marginal rim, which is nearly 

 of uniform width throughout, but is sometimes a little stronger in front of 

 the glabella than elsewhere ; posterior margin very slightly concave in 

 adult specimens, but a little more concave in young ones; near the postero- 

 lateral angle of the head, this margin bends abruptly backward, terminating 

 in cheek-spines of moderate length ; these spines in the adult extend back- 

 ward to a point about opposite the second segment of the thorax, but in the 

 young the spines are proportionally longer, and the whole head larger com 

 pared with the remainder of the body. Glabella slightly elevated above 

 the cheeks, clearly defined by the shallow dorsal furrows ; its anterior end 

 reaching a point about one-half its own length 'from the front margin of the 



