164 NEW YORK STATE MUSEUM 
margins, while the succeeding segments have approximately straight trans- 
verse margins. The segments possess faintly outlined pleural areas denoted 
by a flattening of the lateral region, and a small spine on the postlateral 
angles. The spines of the last segment are distinguished from the others 
by their size, but do not grow into the long lobes which flank the telson 
in other species of Eurypterus. The posterior doublures are short, not one 
fourth as long as the segments. 
The telson is short, having one fourth the length of the body, contracts 
rapidly from the articulation to one half its width and then continues slender 
to the bluntly triangular point. The margins are marked by oblique 
fine incisions that increase in size posteriorly and form a tuft of spines 
surrounding the point. The upper side is flat or slightly concave, the 
underside furnished with a rather narrow, flat-topped carina. 
A ppendages. The appendages of the cephalothorax with exception 
of the chelicerae were well known to Hall. They agree in all features with 
those of the closely related E. fischeri. The preoral appendages 
have been found more or less entangled with the endognathites; a single 
detached chelicera, lacking only the basal segment has however been observed 
[pl. 7, fig. 1]. The pair of pincers is broadest at the base, about twice as 
long as broad; the blades occupy only about one third of the length of 
the pincers; they are broadest at the base, taper rapidly, are edentulous, 
and with very acute tips. The tip of the movable blade is bent inward 
and is needlelike. The endognathites are relatively short and robust; of 
the first pair only the terminal spines or claws project beyond the shield 
border, while the members of the second pair extend for about one half 
their length beyond it, and those of the third pair clear it by fully three 
fourths their length. The fourth pair reaches beyond the third by the 
length of its last three segments. The first three pairs are of equal width, 
and in the first, the segments are twice as wide as long. The spines are 
long, slender, curved, paired and of subequal length, each segment bear- 
ing one pair [pl. 7, fig. 3]. The hooklike long, reflexed evagination of the 
fifth segment of the second endognathite in the male which has been 
