196 NEW YORK STATE MUSEUM 
imatus Hall & Clarke, from the Waverly beds of Pennsylvania. These 
species form a well defined group that is distinctly foreshadowed by one 
of the eurypterids of the Shawangunk grit, viz, E. maria. 
Eurypterus pittsfordensis Sarle 
Plate 13, figures 4-6; plates 14-16; plate 17, figures 1-6; plate 18, figures 3-8 
Eurypterus pittsfordensis Sarle. N. Y. State Paleontologist Rep’t. 
Ig0o2. p. 1098, pl. ro, fig. 7; pl. 15, fig. 1-3; pl. 16-23; pl. 24, fig. 2-5; pl. 2s, 
fig. 2, 5, 6 
Eurypterus pittsfordensis was very fully described by 
its author. We have secured little additional material since the Sarle 
collections were added to the museum and therefore reproduce the original 
description with our observations appended: 
This species 1s comparatively rare and is not represented in the collec- 
tion by any entire individuals. There is, however, sufficient material to 
enable its main features to be correctly determined. | 
The entire animal is large and robust, and broadest at about the 
third segment. The cephalothorax is two thirds as long as broad, eyes 
of medium size, appendages heavy. The preabdominal and postabdominal 
portions are not strongly differentiated; the telson long, probably equal 
in length to the five preceding segments. 
The cephalothorax is broad, rounded in front, the sides curving out 
near the genal angles, and the base straight, or very gently curving over 
the middle portion, and extending a little forward near the sides. The 
margin is beveled in for a distance, in the average sized individual, not 
exceeding 2 mm in the widest part or in front, narrowing and fading 
out at the genal angles. The extreme edge is slightly upturned. The 
compound eyes are separated by one half the breadth of the shield, with 
their bases in line with its center. They are prominent, reniform, broader 
at the anterior ends, and one fifth as long as the shield. The ocelli are 
situated on a faint tumescence between the centers of the compound eyes. 
They are rather large and separated by about their own diameter. Near 
the basal edge of the shield 1s a pair of sharp, raised, triangular scales, one 
on either side of the axial line. In some cases there is a row of shallow, 
flat-bottomed pits on the beveled margin. 
The abdomen increases slightly in breadth from the base of the cephalo- 
thorax to the third segment, then tapers to the telson, there being no appar- 
ent constriction between the preabdomen and postabdomen. The tergites 
