telson. There are only minor differences between the Buffalo and Kokomo specimens; the latter are undoubtedly congeneric and the term Carcinosoma has to yield to Eusarcus.
From the study of the large collection of material representing the genotype we consider the genus as characterized by (1) the triangular carapace, (2) the marginal and forward position of the eyes, (3) the decrease in length of the walking legs backward, (4) the spinosity of all walking legs, (5) the broad elliptic to subcircular preabdomen, (6) the sharply defined, greatly lengthened, cylindrical postabdomen, (7) the broad and short, subtriangular metastoma, (8) the distinctive proportions of the segments of the swimming legs.
These characters, we believe, are correlated and shared by a number of species which thus constitute a well defined group. We have been able to satisfy ourselves as to their presence in Carcinosoma newlini Claypole (including C. ingens Claypole), save the form of the metastoma which has not been clearly seen. Woodward's elaborate description and excellent figures of Eurypterus scorpioides bring out all of these characters save the position of the eyes which were not observed. The inversely triangular form of the metastoma is particularly well established in that species. A like shield-shaped metastoma is assigned by Woodward to Eurypterus punctatus, known only by disjointed parts and regarded by him as closely related to E. scorpioides. Eurypterus obesus H. Woodward may be the young of E. scorpioides, a possibility suggested by the author of the species; at any rate, it strikingly exhibits the characters of Eusarcus, the last drawing published [1872, pl. 30, fig. 8] also showing the characteristic triangular carapace thus leaving only the supposed intramarginal eyes as a discordant feature to which we will return in another chapter. The Pterygotus raniceps H. Woodward, referred by its author to that genus on account of its marginal eyes, leaves no doubt in our mind as to the propriety of its reference to Eusarcus, on account of the triangular form of its carapace, the forward and marginal position
