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 Hall. Palaeontology of New York. 1859. 3: 407*, pl. 81, fig. 1–11; pl. 81A, fig. 1; pl. 81B, fig. 1–5; pl. 83B, fig. 3 Not Salter. Geol. Soc. London. Quart. Jour. 1859. 15: 235 Logan. Geology of Canada. 1863. p. 354, fig. 464.

Description. Body medium sized, ovate-lanceolate in form, robust, not quite four times as long as wide.

Cephalothorax broad and short. Carapace trapezoidal, about two thirds as long as wide (length: width as 6 : 9–10), occupying between one fifth and one sixth of the whole length; broadest at the base. Its lateral margins are nearly straight, slightly converging forward; anterior margins gently convex forward; antelateral angles well rounded; posterior margin slightly concave, bent forward near the genal angles. Profile of carapace not observed. The lateral eyes are small, only one fifth as long as the carapace or less; situated in front of the middle, twice as far apart as distant from the lateral margin, bean shaped, prominent; ocelli situated midway between them.

The preabdomen occupies about one fourth the length of the body. It is slightly wider (about one eighth to one ninth) than long, widening gradually to the fourth tergite and then decreasing again as gradually. The first tergite is seven and one half times as wide as long, the fourth only about six times. The outline of the tergites is the same as in. The sternites are also like those of that species, about four times as wide as long.

The postabdomen occupies one third of the length of the whole body. The first two segments contract at the same rate as the posterior preabdomen, the rest more gradually to nearly one third its anterior width. The telson corresponds in its relative size and character to that of.

Appendages. The cephalothoracic appendages, including the chelicerae, are well shown in several specimens. They differ but slightly from those of.