Page:The Eurypterida of New York Volume 1.pdf/255

 to be inferred from the relative smaller length of the preabdomen that the preabdominal plates were also relatively shorter. The first tergite would, from the evidence of the largest specimen, seem to have been at least eight times as wide as long. The posterior margins (which alone are seen owing to the more abrupt termination) are nearly straight in the anterior tergites but become distinctly concave in the middle of the last two plates; in the sternites they are throughout broadly concave in the middle and well rounded at the postlateral angles.

The gill plates are distinctly outlined in the smallest of the specimens [ pl. 37,] and are of elongate, sublanceolate outline, rounded on the inner side and acutely pointed on the outer, slightly diminishing in size posteriorly.

The postabdomen appears disproportionately long; it is fully twice as long as the preabdomen. At the same time it is broader (one fourth as wide as long) than in other species and has altogether the appearance of a very powerful organ. The first segment completes the contraction of the oval portion of the abdomen as in the other Eusarci, thence the postabdomen is of nearly uniform width, contracting but one sixth to the posterior extremity. The first segment is a narrow ring with a strong forward bend, about four and one half times as wide as long. The next is of similar shape and rate of contraction, but four times as wide as long. At the postlateral angles it is slightly produced backward and its lateral margins are concave, indicating that it had the form of a concave truncated cone. The next, like the following, is of tubular form. The last four segments do not lengthen nearly as rapidly in this species as in, the sixth being twice as long as the third and three fifths as wide as long.

The telson has been seen in but two specimens. In one of these it agrees with the figures given by Claypole of  and   in being short, stout and straight. Its length is one sixth that of the body and four times as great as its basal width. The basal fourth is slightly expanded or inflated, the remainder tapers regularly to a point. One of the specimens shows at the underside near the base a