Boone, Cmstacea, Cruise of "Alva," 1931 73 



ing the branchial region, there is a second carina on each side, 

 which arises just behind the postlateral angle of the carapace and 

 extends backward, sinuate, above the lateral margin, for almost 

 three-fourths of the carapace length. The anterolateral angle of 

 the carapace is rounded. 



The first abdominal segment is, in some specimens, partially 

 carinate in the median dorsal line, and the second and third seg- 

 ments are bluntly, inconspicuously carinate, while on the fourth, 

 fifth and sixth segments this longitudinal carina is sharply and 

 almost completely developed, that of the sixth segment termi- 

 nating in a small tooth. The sixth segment is one and one-half 

 times as long as the fifth segment, but is only about five-sixths 

 as long as the telson, which is channelled longitudinally and has 

 additionally a pair of median lateral, smooth, longitudinal carinae, 

 one on each side of this median groove and about half-way be- 

 tween the carinate margin of this groove and the outer lateral 

 margin. No marginal spines are present on the telson. The caudal 

 fan has the outer blade produced one-third of its length beyond 

 the telson ; the outer lateral margin of this blade is nearly straight, 

 carinate, extending to the extreme tip of the blade and terminating 

 in a distal tooth; a secondary carina extends obliquely from the 

 proximal end of the blade for about three-fourths of its length, 

 terminating in coalescence with the lateral margin. The distal 

 and inner margins are slopingly rounded, ciliated. The smaller, 

 inner blade is intermediate in length between the telson and the 

 outer blade, narrower than the latter and less unequally rounded 

 distally, achieving a nearly pointed, rounded apex. 



The eye is large, the dorsal end of the stalk modified into a 

 flattish, distally rounded, calcareous plate above the cornea; the 

 cornea is concealed beneath this process for the distal two-thirds 

 of its dorsal depth; the cornea is ovoidal, with the ventral and 

 outer lateral surface adjusted to afford an excellent visual range. 



The antennular peduncle is not quite as long as the outer lat- 

 eral margin of the scaphocerite and the inner, proximal angle 

 of this first article is produced into a slender, tapered, acuminate, 

 laminate process heavily setose, that lies flat beside the cornea and 

 extends half its length beyond the cornea ; the second and third 

 articles are shortish, the longer, outer branch of the flagellum is 

 only slightly longer than the lower branch and is but little more 

 than half the length of the peduncle. 



