more prominent than in the other two specimens. This specimen also demonstrates that the scalloping of the edge of the carapace is due to the presence of scales.
The National Museum contains a fragment [pl. 23, fig. 2] of a very large carapace of this species from the waterlime at Buffalo which indicates that the species must have attained much larger proportions than any other known Eurypterus. This carapace was approximately 250 mm wide in front of the eyes, to which a basal width of about 300 mm and a length of the carapace of about 160 mm would correspond. The whole body must have measured fully one meter.
There is no species of Eurypterus which this form closely resembles, and it must represent an aberrant branch of the genus, if, indeed, it actually belongs in the genus at all. Only the carapace and the postabdomen of the animal are known and the appendages may prove to be quite different from those of Eurypterus. In this connection it is suggestive that the Scottish representatives of Laurie's genus Drepanopterus possess some of the features in which E. pustulosus differs from typical Eurypterus [Laurie. 1892, pl. 3, fig. 16; 1899, pl. 3, fig. 17; pl. 4, fig. 22]. Drepanopterus pentlandicus exhibits strong "granular markings" which, judging from his figure [pl. 4, fig. 22], may well resemble those of E. pustulosus in size and distribution, while in D. lobatus the posterior angles of the postabdominal segments are produced into like processes. On the other hand, E. pustulosus does not possess the characteristic form of the carapace of the Drepanopterus-Stylonurus group and in the lobation of the postabdominal segments and its strong ornamentation, it suggests the last Carbonic representatives of the race, notably E. mansfieldi Hall and E. (Anthraconectes) mazonensis.
Eurypterus pristinus nov.
Description. Carapace broadly subrectangular, about one half longer than wide (width, 20.5 mm, length, 13.5 mm). Anterior margin slightly
