Eurypterus dekayi Hall Page 181 See plate 19 1 Hall's type [Palaeontology of N. Y., v. 3, pl. 82, fig. 1]. Interior view of the ventral side of the cephalothorax and of the preabdomen, and ventral view of postabdomen and telson. Natural size Horizon and locality. Bertie waterlime. Buffalo, N. Y.

Eurypterus microphthalmus Hall Page 192 2 Carapace, relatively little compressed and showing the lateral eyes and ocellar tumescence. Natural size Horizon and locality. Manlius limestone. Litchfield, Herkimer cо., N. Y. 3 Type specimen. × 2. [Palaeontology of N. Y., v. 3, pl. 80A, fig. 7] Horizon and locality. Manlius limestone boulder in drift at Cazenovia, N. Y. 4 Large carapace showing broad frontal rim and small lateral eyes. Natural size 5 Large carapace showing somewhat different outline. Natural size Horizon and locality. Manlius limestone. Cranes Corners, N. Y. 6, 7 Types of E. eriensis Whitfield. Natural size Horizon and locality. Hydraulic (Monroe) limestone of Beach point, Put-in-Bay island, Lake Erie, O. 8 Only specimen with abdomen observed. Shows inner view of carapace and ventral view of preabdomen and of three postabdominal segments. Natural size Horizon and locality. Manlius limestone boulder in drift of Onondaga Valley near Syracuse, N. Y. 9 First and second tergites. Natural size 10 Posterior tergite. Natural size Horizon and locality. Manlius limestone. Cranes Corners, Herkimer co., N. Y.

All figures are from photographs. Originals of figures 1, 2, 4, 5, 8–10 are in the State Museum, that of figure 3 is in the American Museum of Natural History and those of figures 6 and 7 in Columbia University