Boone, Crustacea, Cruise of "Alva," 1931 47 



margins moderately convergent anteriorly and less so posteriorly, 

 with a strong, acute spine at the preorbital angle and a small 

 spinule at the base of this outside, and with five sharp, outward 

 and forward directed spines along each lateral margin, three of 

 which are precervical and two postcervical, one each at the antero- 

 lateral terminus of one of the transverse ridges that ornament 

 the dorsal surface. The cervical groove is deep and there are five 

 entire transverse ridges anterior to it, the first of which is sinuate 

 and bears twelve acute teeth, six of which occur at the base of the 

 rostrum ; the outermost pair of the twelve teeth occur, one on each 

 side, midway behind the orbital margin ; the other four ridges are 

 devoid of dorsal spines ; the hinder three ridges are cut by the cervi- 

 cal groove. On the postcervical region there are seven complete 

 transverse ridges and anteriorly, the lateral portions of the three 

 ridges cut by the cervical groove. There is a small, sharp spine at 

 the inner lateral angle of the third of the short ridges, adjacent 

 to the cervical groove ; immediately behind this spine is a second 

 similar spine on the first complete postcervical groove. The linea 

 anom.urica is very distinct. On the lateral walls of the carapace 

 there are several, four to six, oblique ridges running forward. 



The first abdominal segment has a small tooth-like epimera. 

 The second abdominal segment has two small, submedian spinules 

 on each side in the median lateral region of the most anterior 

 transverse ridge, which is sinuate laterally ; there is a deep, me- 

 dian, transverse groove on this segment and a fainter transverse 

 groove posteriorly and a still fainter transverse groove anteriorly, 

 which is nearly obsolete in the median area and recurvate on the 

 broadly rounded epimera. The third segment is smooth, except for 

 two smooth transverse grooves; the anterior groove recurves 

 laterally and extends onto the epimera ; the posterior one curves 

 backward and terminates above the epimera. The epimera are 

 much narrower than those of the preceding segment and rounded. 

 The fourth segment is a little longer in the median line than the 

 third and has the epimera rounded and not quite so narrow ; the 

 dorsal surface is transversed by three lines, which terminate un- 

 equally above the epimera. The fifth segment is still longer medially 

 and has two transverse grooves on the median segment and an 

 incomplete less distinct groove posteriorly which extends on the 

 epimera. The sixth abdominal segment is the longest of the series 

 with the posterior margin truncate above the telson and excavate 



