Page:The Eurypterida of New York Volume 1.pdf/379

 the other parts of the body are approximately uniform in the other species, we infer from their size (13 cm) that it also attained 5 feet in length.

and  vastly surpassed all other arachnids or any organisms of our Upper Siluric era in size and armed with their powerful prehensile pincers, and being evidently active swimmers, as shown by their large swimming legs and telson, they must have been the terrors of the waterlime sea.

Remarks. The principal differences in  and the closely related   are in the form of the carapace, which is less rounded, but more trapezoidal in outline, the frontal margin being less evenly convex; and in the form of the ultimate segment and telson. The telson of the former is not elongate obovate as in, but broadly ovate [pl. 72, fig. 1; pl. 73, fig. 2]. While that of  is about one sixth longer than wide, that of   is as wide as long or sometimes even wider [pl. 72, fig. 3]. Corresponding to this remarkable width of the telson, the preceding, ultimate, segment of the postabdomen is also much wider in  than in , the widening taking place rather abruptly near the middle of the segment.

Hall. Palaeontology of New York. 1859. 3:417*, pl. 83B, fig. 4; pl. 84, fig. 8?

Grote & Pitt. Am. Ass'n Adv. Sci. Proc. 1878. 26: 300, 301, fig. 1

Semper. Beitr. z. Pal. u. Geol. Oestr.-Ung. u. d. Orients. 1898. 11: 80

This species is based on the "free ramus of the chelate appendage." The type, a rather poorly preserved specimen, is from the waterlime at Buffalo and now in the American Museum of Natural History. Hall also