Page:The Eurypterida of New York Volume 1.pdf/412

 proximal end a transverse section of the lamina is seen and a broad cleft exposed while at the distal end the interior margin of one of the laminae is pushed over the other. A third element of the telson consists of a thicker, narrower longitudinal plate intercalated between the dorsal and ventral plates along the median line. The transverse section at the proximal end of the telson fragment gives the view reproduced in text figure 91. The median plate is seen resting on one of the ventral plates without being attached to it, and beneath it the sections of two inclined plates are noticeable. The latter were, we surmise, originally the supporting plates of the median plate, as shown in reconstruction in text figure 92. While this structure reminds one of the T-like keel of the underside of the telson of Eurypterus, it differs from the latter in being introverted between the two plates instead of standing out on the ventral side.

Along the median line of the middle plate, just above the median ventral cleft, a suture passes. The presence of the cleft and of the middle plate with the median suture, all combine to suggest that the two halves of the broad telson may have been capable of being bent slightly in the back stroke of the napping telson.

The margin of the telson has a thickened rim which is cracked at irregular intervals, as in Eurypterus, giving it a serrate appearance.

The third fragment is the proximal portion of a leg [text fig. 93]. It retains the coxa with the gnathobase and portions of the three succeeding segments. The form of the coxa would indicate that it belongs to an endognathite. Its form is elongate quadrangular; the manducatory edge is slightly curved and bears a series of nine or more, rather blunt teeth, which become natter posteriorly. The part adjoining the manducatory edge is furnished with a pavement of flat polygonal scales which are elongate and slightly imbricated near the anterior edge. The rest of the coxa bears small subcircular flat scales and minute tubercles.

The outlines of the following segments of the leg are very faint and can be made out only with difficulty by turning the specimen to the light. The surface of these segments is finely granulate.