Boone, Crustacea, Cruises of "Ara" and "Alva" 251 



on the frontal margin. Below this and anterior to it on the anten- 

 nal angle there is a sharp spine and behind this and the hepatic 

 sulcus is a weaker spine. On the postcervical region there is a 

 very strong lower lateral carina, which arises just behind the 

 cervical groove, this ridge curving posteriorly and extending to 

 the deep groove which parallels the posterior margin. The lower 

 lateral and posterior margins of the carapace form a continuous 

 wide flat carina. 



The abdominal somites are individually sculptured, a pattern of 

 distinctive flat carinae alternating with ridges. The first somite has 

 the anterior two-thirds smooth, convex, this area being bordered 

 posteriorly by a wide deep groove which terminates laterally at the 

 short flat longitudinal carina, which margins the proximal of the 

 short triangulate epimera, there being also a small depression on 

 the epimera, this bordered distally by flat carinae. The second 

 somite is one and a third times as long as the first and is divided 

 transversely into three elevated bands, separated by two trans- 

 verse grooves, the anterior of which borders the posterior of the 

 short, convex, anterior portion of the somite, this groove being 

 continuous in the median region, laterally passing just behind the 

 anterior marginal flat carina of the epimera which the groove 

 transverses obliquely toward the posterior angle. The median 

 elevated band of this somite is about twice as long as the anterior 

 groove, this band forming a rounded lobe laterally, continuous 

 with which there is a narrower, semicircular band on the proxi- 

 mal area of the epimera; the posterior arc of the band uniting 

 with the posterior carina at the proximal angle of the epimera. 

 The second, or posterior groove, is interrupted medially by a flat 

 longitudinal carina, on either side of which the groove extends to 

 the postlateral angle of the epimera; thence is deflected ante- 

 riorly within the arc of the curved median carina ; below the post- 

 lateral angle there is a short, wide carina, directed obliquely to- 

 ward the postlateral apex of the epimera ; a V-shape carina orna- 

 ments the median distal region of the epimera. This epimera is 

 about as wide as the somite with the anterolateral angle rounded, 

 the margins flat carinae, the postlateral angle an acuminate tooth. 

 The third, fourth, fifth and sixth somites are of nearly the same 

 length medially, the respective epimera successively decreasing 

 in size posteriorly and the pattern formed by the grooves and 

 carinae, repeating the same general design, but varied in the 



