218 BB. F. Shumard on the Primordial Zone of Texas, 
genera have been discovered in the Primordial sandstones of the 
northwest except Agnostus and Camerella. 
Compared with the Primordial rocks (Quebec group) of Point 
Levi, Canada, recently so well described by the Canadian geolo- 
gists, the Texan strata may be placed on a parallel with the beds 
provisionally designated as A? by Sir W. E. Logan (this Jour, 
v : : 
Descriptions of New Species. 
TRILOBITES. 
Agnostus Coloradoensis, n. sp. 
Head small, nearly circular, convex, length and breatith nearly equal, 
surrounded with a narrow, neatly defined, flattened border. 
which and the dorsal furrows is a small regularly convex surface. Gla- 
bella convex, narrow-conical, most elevated posteriorly, occupying scar cely 
two-thirds the total length of the head, and not quite as wide as one of 
the cheeks. A single transverse furrow situated near the front divides 
the glabella into two unequal portions, and at the base on either side 1s 
a small triangular Jobe. The glabella is strongly separated from the 
neeks and front border by a deep furrow. 
Length of head, 0°10 of an inch. 
Head large, approaching semicircular, wider than long; glabella some 
what regulatly convex, conical, distinctly separated from the sides and 
; n the sides 
and nearly obsolete in the middle; border in front of the glabella broad, 
ked 
4 “ae: to Eo 
* The genus Bathyurus of Billings appears to me to be closely ped oe 
Saleles of Owen, and both present mauy points of resemblance to Art 
