246 
Kirtley F. Mather 
the inner margin of the border defined posteriorly by a faint, 
rounded depression which becomes obsolete anteriorly opposite 
the third or fourth segment from the front of the pygidium; 
about twelve axial rings and about nine lateral ones are present. 
The surface of the carapace is marked by fine granules which 
are more prominent on the posterior portion of the glabella 
and on the palpebral lobes than elsewhere; no linear arrange- 
ment of the granules is apparent on either pygidium or cephalon. 
The dimensions of the type, a nearly complete cephalic shield, 
are: width, 10.1 mm.; length from anterior margin to posterior 
edge of neck ring, about 6.7 mm.; length of glabella, 4.2 mm. 
An associated pygidium which is selected as the allotype has 
the following dimensions : width, 8.4 mm. ; length, 6.3 mm. ; 
width of axis, 2.6 mm. 
'Horizon and locality. Hale formation: East Mountain, Fay- 
etteville, Arkansas (Stations 136, 137, and 149). Brentwood 
limestone: vicinity of Fayetteville, Arkansas (Stations 135, 
138, 148, and 153) ; Sawney Hollow, Oklahoma (Station 210). 
Kessler limestone: East Mountain, Fayetteville, Arkansas (Sta- 
tion 209). Morrow formation: near Choteau (Stations 298, 302, 
and 306), Hulbert (Station 299), and Ft. Gibson (Station 303), 
Oklahoma. 
Griffithides? sp. 
Plate XVI, figure 15. 
Associated with the type specimen of the last described spe- 
cies was found a fragment of a free cheek of another trilobite 
whose specific and generic relations are uncertain. The free 
cheek, itself, is nearly flat and horizontal, but is bordered by 
an oblique, striated margin of considerable width, which is 
strongly elevated above the cheek and separated from it by an 
angular ridge of increasing height as traced anteriorly. The 
striated border is gently convex and becomes more nearly ver- 
tical toward the front. 
Horizon and locality. Brentwood limestone: Sawney Hollow, 
Oklahoma (Station 210). 
