Page:The Eurypterida of New York Volume 1.pdf/413

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THE EURYPTERIDA OF NEW YORK
405

Besides these three more important fragments there are small patches of lobate fringes such as the posterior margins of the tergites of the later eurypterids frequently exhibit. Their variation in length and form, as well as their characteristic sculpturing, are shown in White's photographs, reproduced on his plate 11, figure 2, 2a, 6-10. The smaller of the lobes, which are invariably blunt and closely arranged, are smooth on the underside and show the impression of spines or short bristles on the other. The adjoining integument shows a pavement of polygonal scales similar to those observed on the gnathobase of the coxa. The largest lobes reproduced by White in figure 2, 2a of plate 11 are rounded and thick and represent a radiating group of stout, hollow processes. These are also covered with oblong, umbilicate impressions, obviously the molts of imbricating plates with perforations that probably were connected with spines.

We may point out in this connection that Salter in 1862 [p. 78] described as Eurypterus (?) from the Coal Measures at the Joggins, N. S., the proximal portion of a telson which seems to be a fair expression of the posterior portion of such a telson as that of Hastimima whitei, even down to the suture of the median carina. We introduce here [text fig. 94] a copy of the Joggins specimen with the outline restored to correspond to that of the telson of Hastimima. This telson fragment is associated with fragments of segments bearing the characteristic thick, drop-shaped or club-shaped tubercles of the later eurypterids. It has been kindly loaned to us by Professor Frank D. Adams from the Redpath Museum of McGill University. We agree with Salter "that it can hardly be supposed to be other than the caudal joint (broken) of an Eurypterus or allied form." It is evident from the specimen that there was an elevated median part, apparently with a sulcus in the middle, flanked by two lateral wings with a flat border.

The Brazilian fragments of the segment and telson are so much alike in their ornamentation that they are safely referred to the same species and genus and properly considered as the type specimens of the eurypterid