Page:The Eurypterida of New York Volume 1.pdf/428

 a very long Upper Siluric time interval, of which a late stage only is represented by the thinner northern extension into the Shawangunk mountains. Here again, as in the fauna of the Normanskill and Schenectady beds, the eurypterids may have changed but very little through several geologic periods; and in all these cases cited, the Shawangunk grit, the Schenectady beds and the Normanskill beds at Kingston, there is identity in lithologic characters and indications of similar littoral conditions, of narrow gulf, or delta, or estuary.

After decades of industrious collecting of eurypterids from the New York Siluric waterlimes, the rich stores of these remains have not been exhausted. While this work was in press and partly in pages, Professor Gilbert van Ingen of Princeton University sent us some slabs from a loose concretion in Oriskany creek in Oneida county, N. Y., which carry three carapaces and other parts of an Eusarcus of very unexpected and peculiar character.

Description. The outline of the body is as in.

Cephalothorax. The carapace is broadly subtriangular, about one third wider than long (not counting a frontal snoutlike prolongation), the two lateral margins converging at an angle of about 700 toward the anterior end which is produced into a linguiform process, about one fifth the length of the carapace. The base is to the lateral margin (excluding the snout) as 4:3. The posterior margin is distinctly bent forward in the middle and the postlateral angles are markedly truncate. The lateral margins are slightly concave in the posterior and as gently convex in the anterior half. The anterior process is one fourth as wide at its base as the basal margin of the carapace. Its lateral margins are nearly straight and converge slightly; the anterior margin is gently convex. The lateral and