THE EURYPTERIDA OF NEW YORK 367 
in form, its proximal margin furnished with a strong process that fits 
into the corresponding notch of segment five, forming a strong articula- 
tion, and its distal margin is produced bluntly to articulate with the 
seventh segment. The latter is the largest one in the swimming leg after 
the coxa. Its longest edge equals in length the preceding five segments. 
It is oval in form, as in other species, flat and expands toward the 
distal end. Its proximal margin is bilobed for articulation with the sixth 
segment and its distal margin is bluntly indented in the middle for the 
articulation with the next segment. The outer lateral margin is slightly 
convex, the inner nearly straight. Both are thickened to strengthen the 
bladelike expansion. The distal portions of the lateral margin are distinctly 
serrate. The rather large triangular process of the inner side of the distal 
margin is, as in the other eurypterids, set off from the rest of the segment 
by a straight suture. The eighth (paddle) is a little shorter than the 
seventh, but markedly more slender; it is long, ovate, with lanceolate 
distal part. Its inner lateral margin is coarsely and its outer margin 
finely, serrate. The single perfect paddle of our material carries at its 
distal end a distinct disklike ‘“‘ terminal palette.”’ 
The metastoma is elongate cordate; its greatest width about one third 
the length from the anterior margin. The width equals three fifths of 
the length. The posterior extremity is well rounded in some specimens 
and apparently truncated in others. The ‘‘ Umschlag”’ or doublure of 
the inner face, is distinctly seen in one of the specimens [pl. 77, fig. 1] 
and the wrinkling caused by the compression of the membrane is visible in 
the figure. In some specimens [pl. 78, fig. 4] a deep median furrow or cleft 
extended about one third of its length. The inner face was smooth, the 
outer sculptured as described below. 
The epistoma has not been observed. The endostoma was, however, 
observed lying under a metastoma and accidentally turned backward [pl. 78, 
fig, 4]. It closely resembles in form the endostoma of Eurypterus 
fischeri. It is a thin suboval shield with deeply emarginate anterior 
margin. Its lateral and posterior boundaries are ill defined, as it there 
