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
Eurypterus pittsfordensis Sarle. N. Y. State Paleontologist Rep't. 1902. p. 1098, pl. 10, fig. 7; pl. 15, fig. 1–3; pl. 16–23; pl. 24. fig. 2–5; pl. 25, 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 is comparatively rare and is not represented in the collection 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 is 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 cephalothorax to the third segment, then tapers to the telson, there being no apparent constriction between the preabdomen and postabdomen. The tergites
