Page:The Eurypterida of New York Volume 1.pdf/181

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THE EURYPTERIDA OF NEW YORK
175

The chelicerae are seen in position in one specimen. The pincers are partly lost and partly obscure, but the full length of the basal joints is shown. A well preserved chelicera exhibiting a broader free blade with slightly curved tips and a narrower straight finer blade is shown in another example. The basal joint is twice as long as the blades and rather slender. This chelicera measures about three sevenths the length of the metastoma. A third detached chelicera, finely exhibiting the blades, is reproduced in plate 12, figure 1. Here the basal joint is broad and relatively short.

The four pairs of endognathites do not differ from those of E. remipes. The first three pairs are relatively short and stout; they increase in length from the first to the third pair at such a rate, that in their usual position their extremities form a straight line nearly tangent to the front of the carapace [pl. 10], the third being about twice as long as the first. The middle segments of the first endognathite are about one third wider than long, those of the third as long as wide. The spines of these endognathites are long and slightly curved and those of the posterior sides slightly longer than those of the anterior. The fourth pair of legs is longer than the preceding pair by one half and slightly more slender. The last clawlike segment is very strongly developed. The coxa of none of these endognathites has been seen fully exposed; nor has the epicoxite been observed.

The swimming legs are broad and powerful organs, though subject to some variation [see var. pachychirus]. They reach to the sixth tergite when reflexed. The coxa [pl. 11, fig. 5] is correspondingly large and strong. In form it does not differ from that of E. remipes. The second to the sixth segments are also like those of that species. The seventh segment which with the eighth forms the paddle is much widened and trapezoidal in outline; its length and width about equal; the posterior side straight or slightly convex, the anterior highly convex, the distal margin straight, with a large subtriangular guide plate for the eighth segment attached to it. The eighth and ninth segments are as in the preceding species.