Boone, Crustacea, Cruises of "Eagle" and ''Ara," 1921-28 123 



margin is more emphasized ; the outlined triangular area is narrower 

 and the upper forward-directed groove extends nearly two-thirds 

 the distance across the segment ; the fifth segment has a curved carina 

 paralleled by a groove extending from the notch on the posterior 

 margin of the fifth segment to the notch on the margin of the fourth 

 segment, and there is also a groove beginning at the notch on the 

 posterior margin of the second segment; another short, forward- 

 directed groove runs from this apex a third of the length of the 

 segment across it ; the lateral margin of the second segment is excavate 

 anteriorly and very convex on the posterior half. The third segment 

 is similarly ornamented laterally and margined as the second; the 

 fourth segment is similar to the third, except that the convex hinder 

 half of its margin is more emphasized; the outlined triangular area 

 is narrower and the upper, forward-directed groove extends nearly 

 two-thirds the distance across the segment. The fifth segment has a 

 curved carina parallelled by a groove extending from the notch on 

 the posterior margin of the fifth segment to the notch on the margin 

 of the fourth segment; there is also a groove beginning at the notch 

 on the posterior margin of the fifth segment and curves forward and 

 down to the anterior lateral margin ; a smaller groove branches from 

 the main groove and runs down onto the posterior lateral lobe. The 

 long sixth segment is much compressed, laterally; has its lateral 

 margin shallowly convex and ciliated; a long curved groove runs 

 from the notch on the posterior margin of the fifth segment to within 

 about two millimeters of the posterior margin of the sixth segment. 

 There is a minute median tooth on the posterior margin of the sixth 

 segment and a fine fringe of plumose cilia across the median part; 

 the lateral part of the posterior margin is produced into two processes 

 at the other margin of the telson and the base of the caudal fan. 

 The telson is about three-fourths as long as the preceding segment 

 and three-fifths as long as the uropoda. It is triangulate, tapering, 

 with the tip bluntly rounded ; the dorsal surface of the telson is con- 

 cave, separated by a pair of longitudinal carinae from the lateral 

 region; a lesser carina on each side extends from opposite the upper 

 angle of the produced larger lobe of the posterior margin to about 

 two-fifths of the length of the telson; a smaller curved, laminate 

 carina extends from the outer basal margin of the telson about three- 

 fifths of the length of the above carina. Just below and beneath 

 this, there is a short groove, and about at its distal termination there 



