106 DISCOVERY OF FOSSILIFEROUS STRATA OF THE 
which is believed to be characteristic of Middle Cam- 
brian strata. The body is elongate ovate, a little over 
three centimeters long in the only entire specimen found. 
The head is large, semi-circular, with large elongate eyes, 
The glabella is elongate, its length about one and two- 
thirds times its least width. Dorsal furrow well defined, 
but not deep. . Glabellar furrows, three or four. Occi- 
pital furrow strongly defined at its outer extremities, but 
narrow and shallow at the center. Occipital ring trian- 
gular; lower than the glabella ; very broad centrally, 
narrowing rapidly toward the lateral terminations ; it 
terminates posteriorly in an obtuse point. The free 
cheeks are triangular, and havealong spine. Hypostoma 
triangular, well rounded anteriorly, with a well-marked 
annulation near the small posterior end. 
The thorax contains eight segments. A linear furrow, 
deeply impressed, passes from one posterior angle of each 
axial segment to the other, traversing the central point 
of the segment in a circular line, convex anteriorly. 
There is a tubercle, or perhaps the base of a spine, on 
each axial segment, just to the rear of its center. 
The pleural segments are depressed, convex, and ex- 
tend at nearly right angles to the axis; they are nar- 
rowed from the anterior side, and prolonged into flat, 
acute, recurved spines, with broad, contiguous bases. 
The pygidium is of moderate size, triangular; axis 
strong, elevated, obconical, with at least two transverse 
furrows anteriorly. The lateral lobes consist of an inner 
depressed convex portion, traversed by two or three 
oblique furrows, and a perfectly flat and moderately 
broad margin, from which three flat and acute spines 
extend backward. 
This interesting trilobite is closely related to Olenoides 
Nevadensis, Meek ; but it differs strongly in the more 
slender thoracic axis, the shape and surface markings of 
the axial thoracic segments, the broad, flat, pleural thor- 
56 
