THE EURYPTERIDA OF NEW YORK 263 
and the metastoma. Another specimen, from Forge Hollow near Water- 
ville, N. Y., nowin the American Museum, exhibits beautifully the second, | 
third and fourth postoral limbs with their spines and lobes, showing novel 
characters especially as to the structure of the fourth limbs. Finally, the 
“museum of the Buffalo Society of Natural Sciences contains a specimen 
with well preserved appendages. With the help of this material the follow- 
ing description of the species can be given: 
Description. Body medium sized, relatively slender, with long ap- 
pendages. Carapace and preabdomen of about equal length, postabdomen 
larger by one half than preabdomen, and telson as long as carapace. 
Carapace of quadrangular outline, relatively long (length to width as 
6:7); the frontal margin broadly emarginate, the rounded anterior angles 
slightly projecting, the lateral margins parallel and nearly straight for 
more than half their length from the base. Doublure narrow. Lateral 
eyes large, about one fifth the length of the carapace, situated close to 
the anterior angles, less than their length distant from the anterior margin, 
and about that distance from the lateral margin. The protuberance is 
oval, and apparently surrounded halfway by the visual surface. 
The preabdomen is little shorter than wide (length to width as 5 : 6) 
attaining its greatest width at the third tergite and contracting thence 
gradually to the postabdomen. Judging from the specimens reproduced 
on plates 42-44, the segments of the preabdomen were highly arched. In 
the flattened condition, they are about six or seven times as wide as long. 
‘Their posterior margin is broadly concave in the middle. 
The operculum is a very long plate; it is hardly more than three times 
as wide as long. The other sternites seem to have overlapped to more 
than half their length and were hence also relatively long plates. 
The postabdomen is the longest division of the body. It surpasses 
by one half the preabdomen, decreases gradually in width to nearly one 
half, while at the same time the length of the segments is ‘doubled, in the 
first segment the width surpassing the length five and one half times, and 
in the last not even one half times (actual proportion 10 : 54; 20:28). The 
