Boone, Crustacea, Cruises of ''Eagle" and ''Ara," 1921-28 89 



inner dorsal angle of this point, another about half as strong on the 

 outer dorsal angle ; below the latter are two very minute spines. The 

 inner posterior dorsal part of the basal joint is produced into a con- 

 vex-concave triarticulate scale that slides over, forming the animal's 

 sound-producing organ. The second joint of the antennae is about 

 one and one-half times as long as the first and less oblique distally, but 

 with a strong spine on the inner distal margin preceded by two less 

 strong ; there is another strong spine in the median dorsal area of the 

 margin with two lesser spines just preceding it, and another weak 

 spine on the outer lateral margin; there are several small spines on 

 the outer lateral and ventral surfaces; the third article is almost as 

 long as the second, almost evenly produced distally, with a series of 

 three strong, subequal spines on the inner lateroventral margin, an- 

 other strong spine on the median dorsal area of the margin, another 

 similar spine on the outer lateral margin; there are seven or eight 

 lesser spines scattered over the surface of the third article ; the flagel- 

 lum is about twice as long as the body and consists of slender, uni- 

 formly tapering rings; the flagellum is set with somewhat regularly 

 placed rings of small spines at intervals and fringed along the proxi- 

 mal part on the inner ventral margin with fine, close-set setae. 



The antennulae have the basal joint extending a trifle beyond the 

 tip of the second peduncular joint of the antennae ; the second article 

 is two-thirds as long as the first and extends to the distal end of the 

 peduncle of the antennae; the third article is a trifle shorter and 

 slenderer than the second; the inner flagellum is longer and stouter 

 than the outer, and is about a third as long as the flagellum of the 

 antennae ; the outer flagellum of the antennulae is a little more than 

 half as long as the inner. 



The epistome is shield-shaped, produced to a decided spine at the 

 apex between the base of the antennulae; there is another spine on 

 each side at the outer margin of the antennulae; the space between 

 these spines is deeply, concavely excavate ; the anterolateral margin of 

 the epistome slopes abruptly diagonally from these spines to the outer 

 lateral angle of the base of the antennae. 



The exopodites of the first pair of maxillipeds are normal with 

 brushes. The second maxillipeds have the exopodite well developed, 

 multiarticulate, with brushes. The third maxillipeds have the exopo- 

 dites very poorly developed. 



The sternal plastron is decidedly shorter and broader than those of 

 P. argus and P. guttatus, anteriorly it terminates in a blunt, rounded 



