Boone, Crustacea, Cruises of " Eagle'' and " Ara," 1921-28 153 



Tlie carapace is moderately compressed, smooth, with a strong, acute 

 preorbital spine ; the postorbital angle bluntly triangular, the ptery- 

 gostomian spine acute. The first and second abdominal segments are 

 of about equal length in the median line; the first segment has the 

 epimeral region curved forward, anteriorly overlapping the posterior 

 margin of the carapace; the second segment has the epimera broadly 

 rounded, subcircular, overlapping both adjacent segments. The third 

 segment is longer in the median line than the second, being produced 

 into a decided hump posteriorly ; the epimeral plates of this segment 

 are rounded, like those of the second segment but not so large. The 

 body is sharply angulated at the union of the third and fourth seg- 

 ments. The fourth segment is two-thirds as long in the median line 

 as the third and has its epimera posteriorly produced and convex, 

 overlapping the fifth segment, which is very similar to the preceding 

 segment but a fourth longer and with a small tooth at the upper pos- 

 terior angle of the epimera ; the sixth segment is very long and attenu- 

 ated, about two and one-half times as long as the fifth segment, with a 

 triangulate tooth on each side projecting upon the side of the telson 

 and a smaller, acute spine at the posterior angle of the lateral margin. 

 The telson is almost as long as the sixth segment, tapering, triangulate, 

 armed with two pairs of articulated spines ; the caudal fan has a short, 

 simple peduncle with a spine at the outer distal angle ; the inner blade 

 is long and slender, with the lateral margins subparallel, the distal 

 margin convex; the outer blade is similar but wider and with more 

 of the distal margin convex. Both are finely ciliated on the margins. 



The eye is on a stocky, cylindrical stalk, a spherical cornea, deep 

 brown. When retracted, the eye lies in a cavity beneath the rostrum 

 and above the excavate peduncular of the antennulae. 



This basal article of the antennulae is much elongated and bears on 

 its outer side a long slender acuminate spine, which reaches as far as 

 the article ; the second and third articles are successively shorter ; the 

 shorter, thicker branch consists of about ten rings and bears a dense 

 brush of setae on the lower margin; the longer branch consists of 

 about 18 to 20 rings and has only a single setum per annulation. The 

 antennulae lie beneath the rostum on either side of its laminate ventral 

 keel. 



The antennae have a rather elongated, cylindrical basal joint, with 

 a spine at its lower, outer distal angle; the scaphocerite is three- 

 fourths as long as the rostrum, narrow, tapered, the outer lateral mar- 

 gin straight, a tiny spine at the distal angle ; the distal margin convex. 



