Boone, Crustacea, Cruises of ''Eagle" and "Ara," 1921-28 155 



the apex, which itself is a large triangulate tooth; the under portion 

 of the carapace produced into a thin laminate blade with the lower 

 margin very convex from the apex to above the cornea, armed with 

 four acute, forward-directed spines, the distal of which is the largest 

 and is placed much nearer the apex than is the most distal spine of the 

 upper margin; the second spine of the lower margin is opposite the 

 first spine of the upper margin; the third spine is smaller and set 

 closer to the second, while the fourth spine is as small as the third 

 and set close to its base, about opposite the base of the first spine of 

 the upper margin. The rostrum is very narrowed above the eye. 

 There is a slightly longitudinal carina on each lateral face of the 

 rostrum, which is continuous posteriorly with the ocular margin. The 

 preorbital spine is conical, acute, directed forward and upward. The 

 postorbital angle is right-angled, slightly rounded. The branchiostegal 

 spine is subequal to the antennal spine; the pterygostomian spine is 

 shorter, but acute and well developed. The crested carina of the 

 median line of the carapace is continued posteriorly for three-fourths 

 of the length of the carapace, but its three spines are placed anteriorly. 

 Carapace smooth, pliable. 



The abdomen has the first segment 2.5 mm. long in the median line 

 with the lateral margin slightly wider, rounded and overlapped on the 

 posterior side by the large projection of the second segment ; the sec- 

 ond segment is 3.5 mm. long in the median line and has the lateral 

 part expanded into a subcircular plate which is ciliate on the margin 

 and overlaps both adjacent segments; the third segment is greatly 

 produced in the median line, being 9 mm. long; the margin is pro- 

 duced to a rounded point in the median line and concave on either 

 side, the lateral part being much narrower, with the lateral margin 

 rounded, ciliated; the fourth segment is narrower, 4 mm. long in the 

 median line, with the posterior margin straight in the median region, 

 notched in the upper lateral region and thence directed obliquely out- 

 ward to the acute point of the lateral plate, which has its outer mar- 

 gin more convex than the inner; the fifth segment is narrower than 

 the fourth and about one millimeter longer in the median line, with 

 the posterior margin similar to that of the fourth segment, except that 

 the postlateral angle is more produced, the acuminate tip larger and 

 the inner lateral margin concave; the sixth segment is veiy narrow, 

 one and seven-eighths times as long as the fifth segment, a produced 

 triangulate process on each side projecting above the outer basal angle 

 of the telson ; the posterior margin above the base of the uropod is 



