Page:The Eurypterida of New York Volume 1.pdf/420

 of these fossils and possibly also graptolites that would indicate the age of the beds. They have indeed afforded a layer with an association of finely preserved seaweeds, the eurypterids herewith described, and the following graptolites:  Lapworth,   Hall,   var. Lapworth,  (Carruthers), the first three forms in great abundance. This graptolite association is one of undoubted Normanskill age. The seaweeds occur in large perfect fronds and are of the same type as those in the Schenectady shale. The eurypterids also are strikingly similar to those from the Schenectady beds.

In one case ( ?  ) we have been unable to distinguish the Schenectady and Normanskill types. This striking similarity of the two faunas (one of Chazy, the other of Trenton age) amounting almost to identity, seems to indicate a very slow progressive development of the eurypterid faunas, probably owing to their early