198 NEW YORK STATE MUSEUM 
three, each joint from the third to the penultimate is provided with two 
long, curved, striated spines. The terminal joints are comparatively long 
and clawlike. The coxal joints are large. The first three are short and 
broad, the length being a little less than two thirds the breadth. They 
have narrow, curved, postlateral prolongations equal in length to the 
second joint. The lower, inner angles are rounded and crenulated. The 
dentate faces at the inner, upper angles are on slight prolongations, which 
grow longer with each succeeding coxa. All three begin with two or three 
isolated, anteriorly directed, lobelike teeth, followed by slender conic 
ones, which become finer toward the posterior end. The fourth coxal 
joint is comparatively long. The inner lower angle is gently rounded 
away, and the neck supporting the narrow dentate face, long. The teeth 
appear to be comparatively few and coarse. The epicoxite of the third 
left coxa is shown on plate 16, figure r. 
The swimming arms are stout and moderately long, extending back 
nearly to the fifth tergite, and consist of nine joints. The gnathobases 
are subquadrate and large, and are provided with seven or eight short, 
bevel-edged denticles, the two anterior being large and prominent. The 
length of the gnathobase was 33 mm, its breadth 30 mm, the length of 
the dentate face 8 mm. The middle joints have the anterior and posterior 
angles sharp, in the fifth the anterior forming a blunt, striated spine, 
much like those at the sides of the postabdomen. The seventh and eighth 
joints are broadly expanded, and their margins, particularly in the latter, 
are marked by sparse, shallow serrations. Inserted on the inner side and 
near the end of the eighth joint, is a small, oval, rudimentary ninth joint. 
The metastoma is elongate ovate, widest in the middle, with ends 
truncated. The anterior or narrower end is notched and minutely dentate. 
The genital appendages of this species, so far as they are preserved 
in the material of the collection, are, with the exception of the part carried 
by the second sternite in the female, essentially like those of E. fisch- 
eri Ejichw., as described by Holm. That of the female is the more com- 
plex and is carried partly by the operculum and partly by the second 
sternite. The part carried by the operculum follows two subtriangular 
areas formed by a pair of sutures extending posteriorly from either side 
the median lobe to meet the cleft, and extends considerably beyond the 
posterior edge of the plate. It consists of a short sagittate base and a 
slender portion divided transversely into two imbricating sections, each 
terminating in a short bifid expansion. In E. fischeri there is a 
third part consisting of two, short, flat, diverging crura. As this appears 
to be a general feature in Eurypterus, it is probable that it exists in this 
species also. The part of the appendage carried by the second sternite 
is covered by that of the operculum. It les in the median cleft which 
extends through the posterior two thirds of the sternite, the anterior third 
