20 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 121 



of sixth somite bilobed, anterior lobe obtusely rounded, posterior 

 triangular, apex spiniform; lateral process of seventh somite not con- 

 spicuously bilobed, margin sinuous, triangular posterolateral apex 

 spiniform; ventral keel of eighth somite inclined posteriorly, rounded 

 anteriorly, angled or rounded posteriorly. 



Abdomen lacking submedian carinae on first 5 somites; remainder 

 of abdominal carinae well-formed, spined as follows: submedian, 6; 

 intermediate, 2-6 ; lateral, 1-6 ; marginal, 1-5 ; sixth somite with sharp 

 posterolateral spine in front of articulation of uropod and short, 

 median, ventral keel. 



Telson noticeably longer than broad, median carina thick, termi- 

 nating in slender posterior spine; carinae of marginal teeth short, 

 rounded, slightly irregular dorsally; 3 pairs of marginal teeth present, 

 prelateral lobes formed dorsally but not projecting laterally; marginal 

 carina almost 3 times as long as carina of lateral tooth; denticles 

 subequal, angular but not sharp, 5, 9-10, 1; ventral surface with 

 short postanal keel, not extending halfway from anus to posterior 

 margin. 



Uropod with 9 graded, movable spines on outer margin of proximal 

 segment of exopod, last short; lobe on outer margin of inner spine of 

 basal prolongation prominent, rounded, inner margin concave. 



Color. — Anterolateral angle of antennal scale black; carapace with 

 U-shaped median dark patch, open anteriorly, anteror to cervical 

 groove; posterior margin of carapace, last 3 thoracic somites, and first 

 5 abdominal somites black; telson with pair of proximal, submedian 

 black squares, convergent rows of pits on surface black; distal seg- 

 ment of uropodal exopod black, with small, clear posterolateral area; 

 distal two-thirds of uropodal endopod black. 



Size.— Males, TL 101.6-128.6; females, TL 126.1-135.6. Other 

 measurements of male holotype: carapace length 24.4; cornea width 

 10.2; rostral plate length 4.6, width 4.1; fifth abdominal somite width 

 24.6; telson length 24.5, width 21.7. 



Discussion. — H. melanoura most closely resembles TI. harpax (de 

 Haan), but it differs in several important features, as follows: (a) the 

 eyes are noticeably larger; (b) the median carina of the carapace is 

 absent; (c) submedian carinae are absent on the first five abdominal 

 somites; (d) the telson is slenderer and longer; (e) the postanal keel is 

 shorter, less than half the distance between the anus and the posterior 

 margin of the telson; and (f) the distal portions of the uropod are 

 black. Specimens of the two species can be separated immediately by 

 the differences in color of the uropod alone. 



Harpiosquilla raphidea (Fabricius) is a larger species, in which the 

 lateral process of the fifth thoracic somite is spined; it is unarmed in 

 H. melanoura. The only other known species of Harpiosquilla, H. 



