The specimen represented in Fig. 1 of Plate IV is here given in outline with the metastoma and maxillæ in position. These parts can scarcely be detected on the finished drawing on acconnt of the obscurity of the specimen, and the falsification which would result if these features were brought out conspicuously.
Fig. 4—Eurypterus Mansfieldi. a.—metastoma. b, b.—maxillæ.
Formation and locality.—Found in the shale immediately below the Darlington cannel coal, near Cannelton, Darlington township, Beaver county, Pennsylvania. Horizon, Alleghany river series.
Eurypterus stylus, n. sp.
Plate V, Figs. 12–15.
Carapace broadly semi-oval or semi-circular; length more than two-thirds the width; margin distinctly limited. Eyes situated on a line across the middle of the length of the carapace and distant about one-fourth the breadth from the margin.
Abdomen wide to the seventh segment, then abruptly narrowed and gradually decreasing in width to the telson. The first somite is anchylosed to the carapace. The widest
