44 



trochanter has a very conspicuous, triangular tooth on the inner side just before the end. Genital 

 coxae (fig. 5 e) much broader than long, anteriorly rather broadly rounded. Exopod of uropods 

 (fig. 5 d) slender, five times as long as broad ; on the outer margin the ciliated part occupies 

 more than two fifths, but conspicuously less than half of the length. 



The petasma (figs. 5^ — 5^) has no pars astringens. Pars externa (e.) is about three 

 times as long as broad, and from a little beyond the middle the feebly convex outer margin 

 converges with the inner margin to the narrow but obtuse end. Pars media is moderately 

 slender; its proximal free part is long, with the outer margin concave to near the base, as this 

 most proximal part is expanded on the outer side and the basal margin is oblique, not concave. 

 Processus ventralis (pv.), which originates at the middle of pars media, is a very long, acute 

 needie reaching to somewhat from the end of the capitulum (c.) and with the base itself widened ; 

 the capitulum is more than three times as long as broad, narrower at the base than before 

 the middle, with the outer margin somewhat convex to the broad, rounded end-, numerous 

 nooks are arranged both on the anterior and the posterior side along the outer margin and 

 on the terminal portion. 



Length 18 mm., a single large specimen 22 mm. 



F e m a 1 e. — Eyes and antennulae in the main as in the females of the preceding forms ; 

 thickened part of the upper flagellum of the antennulae at least as long as second peduncular 

 joint; lower flagellum as long as second and third joints combined, with about 20 joints. Antennal 

 squama reaches about to the middle of third antennular joint. Coxse of third pair of legs (fig. 5 ƒ) 

 as in the female A. vulgaris, with the distal inner tooth very developed ; trochanter as in the 

 male with a very conspicuous, acute tooth on the inner side just before the end. Exopod of 

 uropods as in the male. 



The genital area (fig. 5/) differs much from that in any preceding species. Inside the 

 posterior rounded process from each coxa is seen a rounded protuberance ; the furrow between 

 the penultimate and the last thoracic segments has its middle portion extremely developed, the 

 part of the penultimate segment situated behind each coxal protuberance is elevated as a high 

 and rather large, rounded protuberance directed somewhat. backwards and therefore overlapping 

 a small part of the furrow ; between these two pairs of protuberances the segment is deeply 

 excavated, and this excavation continues on the most anterior part of the last segment which 

 has a pair of oblong, essentially transverse protuberances narrowing the excavation from 

 each side. 



Length generally 25 — 29 mm. ; an extremely large specimen measures 33.5 mm. 



Remarks. — A. spiniger is easily separated from the five preceding species by the 

 tooth on the inner margin of the trochanter of third legs. In the male the clasping organ of 

 the antennulae and the petasma, in the female the genital area afford other excellent specific 

 characters. - - It may be noted that in the large male from the "Indo-Chinese Sea" the third 

 joint of the antennulae is less elongated (only a little more than twice as long as the inner 

 margin of second joint) than in the males from off Rangoon, and its clasping organ on the 

 antennulae is also a little more spinose, but these differences are only variation of slight 

 importance. 



