Page:The Eurypterida of New York Volume 1.pdf/173

 curved appendages of the anterior part of the large median lobe. According to Holm they are tubular, thick skinned organs on the inside of the operculum. The tubes, in this specimen an internal view of the operculum, terminate exactly in the posterior corners of the pentagonal pieces, thus seeming to verify Holm's inference that they emptied there. This operculum also distinctly shows the transverse median line, which here is not simply constituted of a row of scales but begins as a sharp continuous linear depression along which the anterior part projects above the posterior, dying out toward the lateral edges. The posterior paired hornlike appendages are as in other members of the genus.

The appendage of the second sternite has not been seen separately, but its two long and slender terminal pieces are sometimes noticed below the appendage of the operculum in an interior view of the ventral side. Plate 8, figure 4, is a separate second sternite with the basal portion of its genital appendage preserved.

The male appendage has been observed in several individuals. It is best seen in the two detached half opercula [ pl. 6, fig. 7] as a small median lobe with sagittate anterior and straight transverse posterior ends.

Ornamentation. The carapace exhibits a fine granulation along the lateral and frontal margins [ pl. 6, fig. 3, 4] in a belt that is narrowest on the sides and widens in front so that it reaches back to the compound eyes; and a short transverse row of small spines along the posterior edge. The tergites possess a zone of small subcircular scales along the middle portion of the frontal margin and a transverse row of six longer spinelike scales along the posterior margin, which [ pl. 8, fig. 2] are seen to be the posterior terminations of longitudinal rows of smaller scales of the general character. On the postabdominal segments [ pl. 8, fig. 5] these terminal spines die out, but the six longitudinal rows of scales become reduced to two, which are very prominent, diverge backward, are circular at the beginning, lengthen posteriorly and finally overlap. A transverse row of small semicircular scales delimits the exposed portion of the tergites and postabdominal segments from the frontal overlapped portion. The