Page:The Eurypterida of New York Volume 1.pdf/270

 postabdominal segments are furnished with distinct epimera that increase in width with each succeeding member, and are prolonged into short spurs, except on the last segment where they are produced into long, rounded lobes. The posterior doublure is wide, amounting to nearly one half the width of the first segment.

The telson is narrow and long, apparently little shorter than the postabdomen. It contracts rapidly for a short distance from the anterior end, then it continues slender, or increases again slightly to the point which is abruptly rounded. The section is triangular. The dorsal surface is flat or slightly convex, the ventral produced into a flat-topped carina. The edges are sharp and marked by oblique incisions which, toward the extremity, grow into sharp teeth.

The preoral appendages of the cephalothorax have not been seen. The first three pairs of postoral appendages form a series of remarkably stout walking legs that increase in length posteriorly and decrease very little in width distally. They consist of short, ringlike segments, all of which, except the three basal ones, bear a pair of extremely long, curved spines [pl. 45, fig. 3]. The terminal spine or claw also is distinguished by its great length. It is flanked by the almost equally long spines of the last segment. The fourth limb, which has been known hitherto by its basal portion only, displays quite as peculiar characters as the last limb. In length it is intermediate between the third walking leg and the much elongated swimming leg, begins rather slender and becomes gradually wider distally. Though it terminates in a very long and strong claw, thus having the appearance of a walking leg, this claw is not flanked by the two like spines on the last segment as in other eurypterids, but by two broad bractlike lobes. Tracing these legs proximally, the impressions of further bractlike appendages are seen on the inner side [pl. 45, fig. 2, 3], in the places where in the preceding legs the long paired spines are found. Since the opposite sides of the same leg show these bractlike lobes, it is apparent that they represent a modification of the spines of the preceding limbs.