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 opercu- 
lum (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 append- 
age is broken, 0, lateral flanges. x 2 
5 Appendages of a cephalothorax, showing their 
proportions. The chelicerae are not pre- 
served. 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 
Text fig. 123 Diagram to pl 11, 
fig. 4 
463 
