Boone, Crustacea, Cruise of "Alva," 1931 207 



Technical description: This species also belongs to the 

 group with one lateral spine, which in the present species is lo- 

 cated slightly anterior to midway the length of the lateral margin 

 of the carapace. 



The rostrum begins as a laminate carina, just anterior to the 

 cervical groove, and is convex dorsally, tapering on the distal 

 third to an acuminate tapered point that extends straight forward 

 beyond the carapace for only a short distance, reaching to mid- 

 way the length of the cornea. Viewed dorsally, the rostrum forms 

 a narrowed, acute triangle, with its lateral margins continuous 

 with those of the orbital area. There is a deep sulcus on either 

 side of the rostrum, curving back to the main cervical groove and 

 separating the rostral and orbital areas ; the cervical and hepatic 

 sutures are deep. The orbit is dorsally convex, with the frontal 

 margin rim-like, hooding the eyestalk proximally and leaving 

 only the narrowed distal border of the stalk visible. The hepatic 

 sulcus is deep and coalesces with the deeper outer branch of the 

 cervical groove, which delimits the orbit on the lower side and 

 extends to the inferior lateral margin. The anterolateral angle is 

 an acute tooth. The postlateral margin of the carapace is trans- 

 versely excavate in the median area and is broadly rounded on 

 either side. The lateral margin has one tooth, situated slightly 

 anterior to midway the length. The third abdominal segment is 

 produced posteriorly to a slender, acute tooth that projects above 

 the fourth segm.ent for about one-fourth of its length. The sixth 

 abdominal segment is one-fourth longer than the fifth segment, 

 or three-fifths as long as the telson. The telson is long, narrowed, 

 exceeding the length of the uropoda, as figured, and proximally 

 bears a median dorsal channel bordered on either side by a longi- 

 tudinal ridge ; there are two pairs of minute, articulated spines 

 dorsally, spaced as figured. The apex of the telson is stylet-like, 

 flanked on either side by a long, articulated spine. The uropoda 

 have a short peduncle, the inner blade shorter than the telson, 

 very narrowed, with the lateral margins crenulate, converging 

 to a subacute apex ; the outer blade is also shorter than the telson, 

 but is a little longer than the inner blade, with the inner margin 

 crenulate, the distal margin evenly rounded. 



The antennular peduncle has the basal article somewhat con- 

 cave beneath the eye ; the distal margin is produced on the inner 

 ha^f into an auricular process, bent upward and projecting nearly 



