168 Bulletin Vanderbilt Marine Museum, Vol. VI 



Technical description : The largest of the Tahiti specimens, 

 taken by the "Alva," has the following measurements : Rostrum, 

 2 mm. long from tip to the orbital angle ; carapace, 2.5 mm. long 

 from orbital angle to posterior margin; abdomen, 6.5 mm. long; 

 great cheliped : merus, 2.6 mm. ; carpus, 2.5 mm. ; propodus and 

 dactyl, 4.6 mm. long, the dactyl being 2 mm. of this total. The 

 carapace is nearly cylindrical, rather compressed laterally, with 

 the distal two-fifths produced in the median line to a decided ros- 

 tral carina that continues beyond the orbital angle as a laminate 

 blade directed obliquely upward at a decided angle and ornamented 

 on the upper margin with six acute teeth, in addition to the acumi- 

 nate tip, the proximal two of these teeth are above the carapace, 

 the remaining four being subequally spaced, two above the eye 

 and the remainder near the acute tip. There are two similar teeth 

 on the distal portion of the lower margin of the rostrum, one each 

 opposite the distal two teeth of the upper margin. The lateral 

 carina curves behind the orbit, distinct from the margin. The 

 hepatic spine is very acute and set well back on the carapace. The 

 antennal spine is longer than the hepatic and similarly acute. 

 The abdominal terga are smooth, very much compressed laterally ; 

 the sixth segment is no longer than the fifth, or is about two-thirds 

 as long as the telson, which is much narrowed distally, with 

 rounded, ciliate apex. There are three pairs of submedian articu- 

 lated spines on the convex dorsal surface of the telson. The uro- 

 poda have both blades narrowed, ovate, the outer blade being the 

 longer and both successively longer than the telson. 



The eyes are conspicuous, set upon short, bulbous stalks, with 

 the cornea distal, convex; visual range mostly directed forward. 

 The eyes do not extend laterally beyond the carapace. 



The antennulae have the first peduncular article wide, lami- 

 nate, extending beyond the cornea and having a distal and a sub- 

 distal spine on the outer lateral margin; the second and third 

 articles are successively smaller, cylindrical, and extend two- 

 thirds of the length of scaphocerite, or about as far as does the 

 rostrum; the flagellum is two-branched, each branch is finely 

 articulated and extends about one-third of the length of the palm 

 of the great chelae. 



The antennae have the basal article with a small, acute tooth at 

 the outer distal angle ; the scaphocerite is extended almost as far 

 forward as does the distal end of the merus of the second cheli- 



