Page:The Eurypterida of New York Volume 1.pdf/282

 The fourth and fifth segments are well shown, the latter with the typical elongate development seen in Dolichopterus. The sixth and seventh are pushed so into each other that it is impossible to clearly separate them; the eighth is of cup-shaped outline and shorter than the corresponding segment in the genotype, but, as indicated by wrinkles, probably much compressed longitudinally.

A rare and interesting species from Otisville is represented in the collections by three carapaces and one more complete specimen retaining besides the carapace one entire swimming leg and three tergites. From these specimens the following description is derived.

Description. Body small, probably slender. Carapace spadelike in outline, as long as wide, widest on anterior fourth and contracting by about one fourth to posterior margin; frontal margin convex, quite uniformly rounded, sometimes slightly produced in the middle; antelateral angles well rounded; lateral margins gently concave; posterior margin slightly concave in the middle. A broad, level rim of approximately uniform width surrounds the frontal and lateral margins, while the underside of the carapace shows a still wider doublure most expanded in the middle of the front where a triangular lobe extends backward; and which also broadens toward the posterior margin. The lateral eyes are large (one fourth length of carapace), kidney-shaped and situated in the antelateral corners, one third the length of the carapace from the frontal margin and half way between the median line and the lateral margin. The visual surface is crescent-shaped. The ocelli are very distinct, and situated on a circular tubercle between the anterior parts of the lateral eyes. A longitudinal ridge seems to extend thence backward.

Abdomen. The first tergite is very short (six times as wide as long), closely parallel to the posterior margin of the carapace. The following tergites are two to three times as long and slightly increase in width.