LOO PALAEONTOLOGY OF NEW YORK. 



same character and relative position as in Proetus folliceps. The.se furrows 

 would undoubtedly appear in well preserved casts of the lower surface. Occi- 

 pital lobes well denned 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. 



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 pleurae 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. 



PrGlDlUM 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 

 U illiamsville 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 erit 

 Under favorable preservation as many as fourteen annulations may be 

 counted upon the axis. These present the feature noticed in Proetus 

 iceps, being slightly angulated at a short distance within the margin and 

 bent backward over the median line. The pleurse are marked by seven 

 or eight annulations, the postem-lateral area being smooth. All the annu- 

 lations with the exception of the articulating ring, become obsolete upon 

 the border. 



