BY R. ETHEtUDGE, JUNR., AND JOHN MITCHELL. 499 
and sloping upwardly at an angle of 60° to 70°; height of each eye 
about two- thirds of its length, in front barely reaching the front 
angles of the glabella, posteriorly in a line with the central por- 
tion of the intercalary furrow. 
Thorax. — Of eleven segments, width seems a little greater 
than length; axis prominent, contracts very gradually posteriorly 
from the sixth segment, terminating with a width about 
four-fifths of the anterior width; segments nodular at the 
ends; lateral lobes very little wider than the axis, hori- 
zontal between fulcra and axial furrows, deflected portion 
steep, component pleura imbricate and rounded at the ends; 
pleural furrows distinct and wide, seeming to reach nearly to 
the ends; anterior ridges of pleurae triangular, posterior very 
narrow; interpleural sutures and axial furrows distinct. 
Pygidium. — Subsemicircular or subquadrilateral, width greater 
than twice the length; axis tolerably prominent, seven seg- 
ments visible, terminating bluntly with about half the anterior 
width at the border, slightly sunk between the lateral lobes, 
which are moderately inflated, horizontal between fulcra and 
axial grooves, anteriorly deflected to correspond with pleurae of 
thorax, but posteriorly becoming less steep; five to six pleurae 
visible on each lobe, only the two anterior ones showing the pleural 
furrows and sutures distinctly, the furrows reach the border, 
anterior face straight, axial grooves moderately distinct. The 
whole surface shows evidence of granulation. 
Obs. — This species approaches P. fecundus, Barr., very closely, 
but we consider there are sufficient differences between them to 
justify us in giving specific rank to our form. Its most con- 
spicuous feature is the great size of the eyes, in which respect it 
surpasses P. fecundus, Barr., and many other species of the genus, 
and as in all the mature specimens that have come under our 
notice, twenty-two vertical rows of lenses containing twelve in 
each row are constant features, while in P. fecundus, Barr., 
nineteen vertical rows with nine lenses in a row are the normal 
features, we consider this to be a sufficient difference for specific 
