The Eurypterida of New York/Volume 2/Explanations of plates/Plate 11

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PLATE 11

Eurypterus lacustris Harlan
Page 173
See plates 9, 10, 12, 13

1 Young individual. Original of Hall's figure [Palaeontology of N. Y., v. 3, pl. 81, fig. 1] × 2. Shows well the outline of the carapace and the relatively large size of the compound eyes in the young. The preabdominal segments are shoved together, and the preabdomen appears therefore too short and wide and too abruptly contracted. The apparent posterior edges are partly fracture lines. The outline drawing of the specimen, inserted in the text, shows this condition more distinctly.
2 Ventral side of a specimen, showing the five sternites with their median sutures. The first four retain a certain amount of uniform convexity, the fourth is pushed inward and much arched, the fifth flattened and shows the relatively great length of these segments. The genital appendages of the first (opercular) and second sternites are broken out, leaving a cleft. Natural size
3 Operculum, original of Hall's figure, op. cit. pl. 81, fig. 8 [see diagram, text fig. 122]. The pentagonal pieces in front of the opercular appendage are seen. The principal median appendage is broken at b, its original extension indicated by an impressed line at с The paired tubular

Text fig. 122 Diagram to pl. 11, fig. 3

appendages are recognized in outline at a, and the aperture seen at h. The posterior (e) and lateral (d) doublures, as well as fragments of the anterior connecting membrane, are also shown. Natural size

Memoir 14. N.Y.State Museum. Plate 11.
J.A.Glenn phot. J.B.Lyon Co. State Printer.
4
Text fig. 123 Diagram to pl. 11, fig. 4
Interior view of female opercular appendage. Original of Hall's figure, pl. 81, fig. 6 [see diagram, text fig. 123]. The outlines of the paired terminal appendages of the operculum (3 in diagram) and of the paired appendages of the second sternite (shaded in diagram, marked c) are seen; a, line along which the principal median appendage is broken, b, lateral flanges, × 2
5 Appendages of a cephalothorax, showing their proportions. The chelicerae are not preserved. The walking legs are seen from the underside and exhibit the bases of the smaller spines. The balancing legs are mostly broken away, and only the coxae preserved of the swimming legs. Natural size

All figures are from photographs. The originals are from the Bertie waterlime at Buffalo, Erie co , N. Y. Those of figures 1, 3 and 4 are in the American Museum of Natural History, that of figure 2 in the State Museum and of figure 5 in the Buffalo Society of Natural Sciences