66 PERMIAN FOSSILS. 
No. 1. Diruyrocaris Permiana, v06. Tab. XVIII, fig. 1 a, 4, ¢, d. 
INCH. 
Length of carapace-valve, > 
Breadth — si 
Carapace-valve (left) oblong, convex, suddenly depressed along its anterior, 
posterior, and outer margins; bordered on its outer (left) edge by a slight ridge; 
smooth, faintly reticulated. Devtral (dorsal) edge nearly straight; sinistral straight 
in the middle, and curving off at each end to meet the dextral border. Lztremities 
obliquely rounded ; the azterror, in some specimens, almost squared ; posterior extremity 
of the dorsal edge more acute than the anterior. 
Internally the valves exhibit considerable thickness at the posterior extremity. 
The valves of this species vary somewhat in the relative measurements of length 
and breadth, and sometimes the valves havean increased breadth posteriorly. 
We have not met with a complete carapace ; and entire valves are of rare 
occurrence; casts, however, more or less perfect, are very common at Byers’ Quarry. 
No. 2. DirHyRocARIs GLYPTA, vob. Tab. XVIII, fig. 12. 
INCH. 
1 
Length of carapace-valve, =) 
Breadth — 
50 
Carapace-valve (left) oblong, convex, finely reticulated, bearmg five curved 
longitudinal ridges. One ridge on the outer (left) border, and a second, a little within 
the first, extend from the junction of the dextral and anterior borders, following the 
curvature of the edge of the valve, to the posterior angle of the dextral border; the 
third and fourth ridges follow a like course, at equal distances, within the former 
ridges; the third ridge faintly marked posteriorly, and the fourth rather sinuous; a 
fifth ridge is placed a little to the right of the fourth, but is interrupted anteriorly. 
Sinistral border of the valve slightly incurved; posterior extremity obliquely curved, 
narrower than the anterior. 
In this and the preceding species the angle of the anterior extremity of the 
dextral or dorsal border is more or less prominent, and not, as in other species, 
removed so as to form a large central notch when both valves are in juxtaposition. 
From the same locality as the last. 
