THE EURYPTERIDA OF NEW YORK 167 
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 oper- 
culum. 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 oper- 
culum 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 append- 
ages 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 ven- 
