Page:The Eurypterida of New York Volume 1.pdf/269

 and the metastoma. Another specimen, from Forge Hollow near Water ville, N. Y., now in 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 following description of the species can be given:

Description. Body medium sized, relatively slender, with long appendages. 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