Page:The Eurypterida of New York Volume 1.pdf/277

 The carapace is subquadrate in outline, narrowing slightly toward the base. The frontal margin is the most convex, increasing in prominence with advancing age and in the largest specimens becoming distinctly angular. The antelateral angles project but are well rounded; behind them the carapace contracts somewhat rapidly and widens again in the posterior half forming low cheeklike projections of the lateral margins. The posterior angles are subrectangular and but little rounded. The posterior margin is gently concave or straight. A fine thickened filiform rim surrounds the lateral and anterior sides. The produced frontal part of the carapace is flat or depressed and continuous with a flat border on the sides. The remaining part appears to have been moderately elevated and to have culminated behind the ocellar mound. The doublure of the underside is broadest in front, corresponding in extension to the flat frontal border and is narrower on the sides. It possesses one to two deep wrinkles that cross the frontal portion transversely. The lateral eyes are situated in the anterior corners, near the margin, separated from the latter by about twice the width of the flat border. They are very large (one third the length of the carapace), prominent, semielliptic in outline, the outer side convex, the inner straight. The visual surface is crescent-shaped, situated on the outer slope. The supporting ridges are apparently very strong, especially so along the convex outer margin. In one specimen the surface exposed is ornamented with low, small, very closely arranged circular tubercles.

The first tergite is a very short band of subequal length, nearly eight times as wide as long. The second tergite is twice as long and considerably wider.

Measurements