100 
PALEONTOLOGY OF NEW YORK. 
same character and relative position as in Proetus folliceps. These furrows 
would undoubtedly appear in well preserved casts of the lower surface. Occi¬ 
pital lobes well defined but relatively small, and somewhat concealed by the 
prominent basal margin of the glabella; occipital furrow narrow upon the 
axis and but slightly widening upon the cheeks; occipital ring broad upon 
the axis and narrowing upon the cheeks. 
Cheeks depressed at the summit about the base of the orbital ridge, 
sloping for a short distance abruptly, and thence more gently to the broad 
marginal sulcus. 
Eyes elevated, not large, approximate, probably attaining the height of the 
glabella. 
Thorax trapezoidal, lateral margins approximating; very strongly arched upon 
the axis, flattened upon the pleurie for about one-half their width and 
deflected toward the margins. Composed of ten segments which are trans¬ 
verse, somewhat flattened and grooved upon the pleurae. 
PvGiDiUM semi-ovate to semi-elliptical, convex and sloping evenly to the lateral 
and posterior margins ; equally trilobate ; border thickened, moderately wide, 
its width slightly increasing posteriorly. In specimens from the Corniferous 
limestone of Ohio the axis is strongly arched, both longitudinally and trans¬ 
versely, and tapers to an obtuse and somewhat elevated termination. While 
many of the New York specimens conform with this type, examples from 
Williamsville have the axis broader, more depressed, the margins tapering in 
a broad, outward curve to a low, blunt apex, in these respects affording a 
close resemblance to the pygidium of Proetus Conradi of the Schoharie grit. 
Under favorable preservation as many as fourteen annulations may be 
counted upon the axis. These present the feature noticed in Proetus 
folliceps, being slightly angulated at a short distance within the margin and 
bent backward over the median line. The pleurae are marked by seven 
or eight annulations, the postero-lateral area being smooth. All the annu¬ 
lations with the exception of the articulating ring, become obsolete upon 
the border. 
