Page:The Eurypterida of New York Volume 1.pdf/190

 contraction and imperfect preservation. In the hypotype the dimensions of the preabdomen are 42 × 63 mm. The postabdomen of the type is 50 mm wide at the proximal end, 56 mm long and 17 mm wide at the distal end. That of the other specimen is too long by distention, its proximal width being 50 mm, its distal 17.5 mm and its length 73 mm (probable normal length about 65 mm). The telson of the type is 53 mm long and 10 mm wide at its proximal end.

Horizon and localities. The two known specimens are from the Bertie waterlime of the neighborhood of Buffalo.

Clarke. N. Y. State Mus. Bul. 107. 1907. p. 305, pl. 1, fig. 1, 2, 4; pl. 2, fig. 2, 4, 7; pl. 3, fig. 1–5, 7

The preliminary description of this form in Bulletin 107 is as follows:

The general form of the largest observed individuals of this species is elongate and slender with very little abdominal expansion and no lobation of the segments. In these ephebic conditions the head is somewhat elongate, regularly rounded in front and with subparallel lateral margins. The eyes are crescentic, subcentral, as far asunder as the inner margin of each is from the margin of the shield.

The ocellar lobe is well denned at an early stage. A specimen 63 mm long without the telson, apparently mature, has 11 segments, but a break across the body leaves room enough for a 12th. The width of the base of the head is 15 mm and this is but very slightly less than the greatest expansion of the abdomen. Little trace of surface sculpture is visible on any of the parts.

Description. Body. The body is terete or subcornical, with subcircular sections in all parts save the carapace. It is about five times as long as wide, and tapers very gradually from the base of the carapace.

Cephalothorax. The cephalothorax is broadly semielliptic to semicircular in outline, about one third wider than long, widest at the base and evenly rounded. While it is as broad as, or broader than, the widest part of the abdomen, it attains but one sixth to one seventh the length