there was only one large and typical eurypterid fauna, that of the Bertie waterlime, known from the rocks of this State, and except the small fauna of the waterlime of Kokomo, from the entire continent. Of so much greater interest therefore is the discovery within a few years of three new and larger faunas. The first is that of the Pittsford shale at the base of the Salina beds in Monroe county, found by Clifton Sarle. Its most striking and common member is the representative of a new genus, termed by its discoverer Hughmilleria. This is a form which has a very interesting bearing on the phylogeny of Pterygotus and Slimonia. The eurypterid portion of the remarkable arthropod fauna of Pittsford has been elaborately described and figured by Mr Sarle in the Report of the State Paleontologist for 1902. It consists of the following species:
| Hughmilleria socialis | Pterygotus monroensis |
| H. socialis var. robusta | Stylonurus (multispinosus C. & R.) |
| Eurypterus pittsfordensis |
The associated forms (crustacean species of Ceratiocaris, Pseudoniscus, Emmelezoe, Bunodes, mostly described by Clarke), the peculiar lithologic surroundings of this fauna, and the fact that through this discovery the salt and gypsum-bearing Salina beds are now known to be both underlain and overlain by Eurypterus beds, all bear on the problem of the physical conditions under which these animals lived.
A second discovery was made in 1906 by the junior author of this book in the shales of the Shawangunk grit formation of southeastern New York. A preliminary description of this fauna was published by the senior author in 1907 [N. Y. State Mus. Bul. 107]. It consists of one species of Eurypterus, one of Eusarcus, one of Dolichopterus, six of Stylonurus, one of Hughmilleria and one of Pterygotus. It has furnished a contribution to the organization of the eurypterids in a specimen of Stylonurus, retaining all four posterior legs of one side, in the light of which previous restorations of that genus are greatly modified. The most novel feature of the Shawangunk grit fauna, is the presence of larval stages of
