THE EURYPTERIDA OF NEW YORK 271 
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 cara- 
pace contracts somewhat rapidly and widens again in the posterior halt 
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 surtace 
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 
Type : . millimeters 
Length of carapace.......... ee eee eee eee e ee eee 15.2 
Width of carapace... .. ccc ccc cee eee eee eee 15 
Length of eyes... cece ce eee eee ee ee 4.6 
