36 



most half as long again as the inner margin of second joint. Thickened part of the upper 

 flagellum about as long as the inner margin of second peduncular joint. Lower flagellum con- 

 spicuously longer than third peduncular joint, with i6 — 20 joints; its proximal part constitutes 

 a shaft for the clasping organ and is distinctly 3-jointed (fig. 2d)\ the main "branch" of the 

 organ has its pro.ximal 4-jointed part conspicuously and evenly curved, and the joints decrease 

 gradually in thickness; the tifth joint of this "branch" is nearly thicker than the fourth, with a 

 close row of 4 or 5 strong spines directed downwards and often somewhat outwards, while each 

 of the three preceding joints and the sixth joint has a single, much shorter spine, and the part 

 beyond fifth joint contains 8 — 1 2 joints ; obliquely below and outside the base of the main 

 "branch" originates a single very strong and long, moderately curved spine, which reaches 

 almost the above-named row of spines. The antennal squama reaches always rather considerably 

 beyond the end of second antennular joint, but never to the middle of the third. Coxee of third 

 pair of legs (fig. 211) with a very distinct, triangular, acute tooth on the distal inner angle, and 

 the proximal inner corner is rectangular; the trochanter has no tooth near the distal end of its 

 inner margin. Genital coxae (fig. 2«, gc.) obliquely triangular, a little longer than broad, distally 

 produced into a somewhat narrow, a little curved, subacute process. Exopod of uropods (fig. 2m) 

 somewhat more than four and a half times as long as broad, and on the outer margin the 

 ciliated part occupies about two-fifths of the whole length. 



The petasma (figs. 2p — 2r) is proportionately well developed. Pars externa {e.) is large, 

 about twice as long as broad, with the distal inner angle subrectangular, and more than the 

 distal third of the outer margin is somewhat convex. Pars astringens {a.) has a very long inner 

 margin equipped with coupling hooks. Pars media has its proximal portion free and rather 

 broad, with the basal margin somewhat concave so that two protuberances are formed, the 

 inner short, the outer much longer, oblong-triangular, and directed much outwards. Considerably 

 beyond the basal portion described is seen at the outer margin a piece connecting pars media 

 with the pleopod. The capitulum {c.) and processus ventralis [pv.) are combined comparatively 

 small, not much more than one-fourth of pars media; proc. ventralis is very robust, oblong- 

 triangular, a little curved, acute, without armature; the capitulum itself is distinctly but not 

 much longer than proc. ventralis, scarcely even one-third as long again as the process, thick, 

 only a little more than twice as long as thick, much narrowed beyond the middle, but the 

 distal part is moderately thick though at its middle less than half as thick as the proximal 

 part, and broadly obtuse; seen from behind (fig. 2^) some quite small hooks are perceived near 

 the end, but seen from in front (fig. 2 r) two extremely large hooks are observed at the outer 

 margin beyond the processus ventralis, more distally a distinctly or much smaller hook, and at 

 the end some small hooks. 



Length of a large male (from the Gulf of Siam) 24.5 mm., but sometimes the sex is 

 considerably smaller, a small male from Surabaya being only 17.3 mm. long. 



Female. — The sex difters from the male in the antennulse, the coxae of third legs 

 and, of course, the genital area. The peduncles of the antennulae (fig. 2d) are somewhat shorter, 

 so that the antennal squama reaches distinctly beyond the middle of third joint; second and 

 third joints less robu.st than in the male and combined nearly as long as the outer margin of 



