94 
PALEONTOLOGY OF NEW YORK. 
The latter species has the same number of annulations on both axis and pleurae, 
and the same general outline; its axis however is more slender, the axial annu¬ 
lations transverse, and the border less conspicuous and more flattened. 
Distribution. Upper Helderberg group. In the Schoharie grit, at Schoharie, 
Schoharie county. 
Pkoetus, sp. ? 
PLATE XXII, FIGS. 5, 6. 
A SINGLE imperfect cephalon, and two pygidia from the Schoharie grit, differ¬ 
ing from those of any species previously described from this horizon, indicate 
the existence of at least one additional species of Proetus. 
The Cephalon is semi-elliptical in outline, the glabella ovoid and very convex, 
its anterior extremity tangent upon the frontal border, and the surface without 
apparent traces of transverse furrows. The frontal border is very broad and 
sloping; eyes relatively small, orbital ridge unusually conspicuous, beneath 
which the surface of the cheek is grooved, somewhat flattened and thence 
abruptly deflected to the marginal sulcus; its extremities were evidently pro¬ 
duced into short spines. The occipital furrow is narrow and sharp; the occipital 
ring broadly rounded. The specimen measures 12 mm. in length and 28 mm. 
in width. 
The Pygidia exist in the form of casts, and there is no evidence that they 
belong to the species represented by the cephalon. They are much shorter 
than in P. angustifrons or P. Conradi, show but six annulations upon the axis 
and three or four upon the pleurae. 
Distribution. Upper Helderberg group. Schoharie grit; The cephalon is 
from Schoharie, Schoharie county; the pygidia from the towns of Knox and 
Clarksville, Albany county. 
Proetus' curvimarginatus, n. sp. 
PLATE XXII, FIGS. 13-19. 
General Form and Proportions. Body ovate or sub-elliptical. 
Surface sub-equally trilobate, convex along the axial line, strongly deflected 
at the margins. Length to width as 2 to 1. 
