From the Upper Devonian rocks of Ohio. 39 
slightly elevated areas, with depressed sulci between; an ante- 
rior, a central and a posterior one. e first is situated in the 
middle of the anterior end of the shell; the central one unites 
with the anterior one below, and extends along the basal mar- 
gin behind, in a narrow curved point below the posterior one, 
and projects upward near the center of the valve in a triangular 
form, terminating in an elevated point just above the median 
line; the posterior and largest area is ovate in form, and occupies 
a little less than one-half the length of the shell, is narrowed 
in front and pointed behind, taking the form of the extremity 
of the shell. The center of the anterior area is slightly tumid. 
which extends to near the point of the central raised area 
fore mentioned. These three nodes, together with the 
oblique, ridge-like one terminating the marginal rim, border 
the hinge-line on each valve. General surface of the valve 
finely punctate, but most distinctly so on the posterior field. 
The elongated form of the carapace readily distinguishes 
this from any of the other species described, while the number 
of node-like ridges is a very marked feature. The abdomen 
and telson of this species have not been observed, although 
several imperfect carapaces, mostly showing parts of both valves, 
have been obtained. — : 
Formation and locality,—In calcareous concretions in the Erie 
shales, at Leroy, Lake County, Ohio. 
ssociated with the Entomostraca, above described as from 
the concretions of the Erie shales of Ohio, are the remains of a 
Macrouran Decapod, which appears to differ so much from any 
described genus as to make it undesirable to refer it to any of 
them. One of its peculiarities consists in the possession of a pair 
of very strong antennal appendages which project from beneath 
the anterior end of the thoracic carapace, of such size and strength 
as to raise considerable doubt as to their true nature. The exist- 
ence of five thoracic limbs, exclusive of these, projecting from 
beneath the carapace on one side would seem to place their pedal 
nature out of the question; while their great development as 
seen on the specimen would indicate that they had served 
Some purpose other than simple antennez, and to raise the 
