368 NEW YORK STATE MUSEUM 
was connected or gradually passed into the thin ventral integument of 
the cephalothorax. The inner margin of the frontal notch is thickened 
and a median thickening proceeds from it, posteriorly ending in a thickened 
semioval plate. | 
The opercular appendages of only two specimens have been observed. 
These represent the female appendages of young examples. The best 
preserved and oldest specimen gives two aspects of the appendage, the 
exterior on the mold of the fossil, and a partially interior one on 
the cast. Both together show that the appendage was broadly hastate 
at the anterior end, extending to nearly the anterior margin of the oper- 
culum and was produced posteriorly with a clublike process which, in the 
young individuals at least, did not extend beyond the posterior margin of 
the operculuin. This process was overlapped on both sides by the inner 
margins of the two opercular plates, which left only the narrow median 
portion exposed. 
In the largest of the specimens, a distinct sigmoid vermiform depres- 
sion is seen to proceed on one side from the anterior end of the appen- 
dage, passing just within the anterior margin of the opercular plate for 
some distance and finally swinging backward, gradually tapering toward 
its extremity. This depression corresponds in location and form to one 
of the paired horn-shaped organs observed by Holm in E. fischeri 
on the inside of the operculum on either side of the opercular appendage. 
It could be well conceived that its presence prevented the filling of the 
space with mud for a time and its final collapse produced the depression. 
The opposite opercular plate is bent over and crumpled so that this horn- 
like organ is not there observable. 
Sculpture. The sculpture of the carapace consists only of fine 
tubercles which are most distinct and closely arranged along the margins 
and between the eyes; that of the remainder of the integument is composed 
of linear, crescentlike or angular scales. 
The scales of the tergites are small, mostly linear or flat crescentic 
and distributed on the anterior half of the tergites. The sternites are entirely 
covered with large, prominent scales except in a belt along the posterior | 
