Boone, Crustacea, Cruise of "Alva," 1931 193 



Technical description : Carapace cylindrical, definitely com- 

 pressed laterally, produced dorsally to a short, triangulate ros- 

 trum, which is crested ; there is one epigastric spine and the short, 

 laminate, crested rostrum bears two coarse, subequal, triangu- 

 late upward-directed teeth, which are larger than the epigastric 

 tooth, in addition to the rostral apex, which itself forms a slightly 

 longer, slenderer tooth, directed straight forward, with the apex 

 not extending any farther forward than does the cornea. There 

 is a very strong, acute, supraorbital spine. The infraorbital 

 angle is not spinose. There is a small, sharp antennal spine. The 

 anterolateral angle of the carapace is rounded. The abdominal 

 segments are moderately compressed laterally and the third seg- 

 ment is produced to a small median point posteriorly; the sixth 

 segment is only one and one-fourth times as long as the fifth, or 

 four-fifths as long as the slender, tapered telson, which bears 

 dorsally three pairs of subequally spaced, articulated spines ; the 

 distal telsonic margin is truncate and set with six close-set spines, 

 the innermost pair of which is the longer. The uropoda are 

 slender, both blades being narrowly ovate, the inner one being 

 about one-sixth longer than the telson, and the outer blade, which 

 is the wider, longer than the inner blade in the same ratio. 



The eyes are large, forward-directed, set on thick, cylindrical 

 stalks ; the cornea is terminal, hemispherical, longer on the lower 

 and outer than on the upper side ; distally no longer than the ros- 

 trum; also equal in length to the basal peduncular antennular 

 article. 



The antennulae have the first peduncular article laminate, 

 deeply cleft on the outer lateral margin, this terminating in an 

 acute, spine-like tooth that projects obliquely forward almost as 

 far as the outer distal tooth of the short, thickened second joint; 

 the third joint is closely fused with the second joint and quite 

 convex dorsally, tapering to an acute median spine distally; the 

 flagellum is two-branched, the upper branch is about one and one- 

 third times as long as the peduncle and very thick, closely fused 

 articles having the aspect of a clumsy, thick, scaphocerite, the 

 proximal four or five articles being dorsally convex, the distal 

 two-thirds of the wide portion less so, thick, followed by a nar- 

 rowed, thread-like whip that comprises the distal fourth of the 

 flagellum and extends not quite so far as does the scaphocerite. 

 There is the appearance of a groove or cleft obliquely on the upper 



