Boone, Crustacea, Cruise of "Alva," 1931 189 



region; the fourth segment is only four-sevenths as long in the 

 median line as the third ; the fifth segment is only three-fifths as 

 long as the fourth ; the sixth segment is only one and three-fifths 

 times as long as the preceding segment, truncate above the base 

 of the telson and produced in a longish, acute triangulation on 

 either side above the outer angle of the telson. The telson is one 

 and one-half times as long as the sixth segment ; the dorsal sur- 

 face is rounded with a slight median depression proximally, semi- 

 concealed beneath tufts of setae; there are two pairs of coarse 

 articulated spines present, the proximal pair being not quite half- 

 way the length of the telson ; the second pair being half-way be- 

 tween the first pair and the distal margin. The latter is narrowed, 

 truncate and bears a pair of long submedian, articulate spines, 

 and outside of these, one on each side, is another pair of minute 

 articulate spines; the distal half of the lateral margin and the 

 distal margin are heavily fringed with long, coarse setae. There 

 is a strong, triangulate-articulate spine on either side at the outer 

 proximal angle of the uropod peduncle, projecting upon it for half 

 its length ; the distal margin is unequally bifid ; the blades are sub- 

 ovate, each about one-sixth longer than the telson, the inner blade 

 is the smaller, regularly ovate, the wider outer blade with a strong 

 subdistal tooth at the outer lateral angle, from which a curved 

 sulcus runs back to the base ; the distal portion of the blade is 

 separated by a sinuate suture; both blades are heavily setose on 

 the distal half of their respective margins. 



The eye is set on a short thick stalk which bears ventrally a 

 strong, median spine on its distal margin ; the cornea is deep, hemi- 

 spherical, set obliquely terminal ; there is a small circular ocellus 

 on the dorsal surface of the stalk ; the ventral half of the cornea is 

 deeper than the dorsal half. 



The antennulae have the basal article laminate, dorsally con- 

 cave on the inner two-thirds with a very deep, narrow incision 

 separating this from the outer distal angle, which is greatly pro- 

 duced in an acute, strong, outer spine that reaches as far as the 

 distal border of the third peduncular article, and bears on its 

 inner side another short spine, which is wider, triangular, and 

 extends only about as far as the distal margin of the inner portion 

 of this article ; the second and third articles are short, thick ; the 

 third article bears distally on the dorsal surface a fleshy triangu- 

 late process that projects a short distance above the base of the 



