ii6 



on the upper flagellum as usually depressed, on the lower compressed ; the first joint as usually 

 long, in the upper flagellum somewhat slender, in the lower conical and unusually thick at the 

 base; the second joint is short, the four following joints increase gradually in length, and the 

 sixth joint is as long as, or slightly longer than, the seventh. The antennal squama (fig. 2^/) is 

 considerably broader than in the three following species, being scarcely seven times as long as 

 broad, with the large terminal lobe beyond the marginal tooth more than half as long again as 

 broad; the squama reaches in the female (fig. 2 b) at least slightly beyond the middle of third joint 

 of the antennular peduncle, in the male (fig. 2 a) distinctly beyond the end of the peduncle. . 



Fig. 2 e shows one of the false chelae of the elongated .second pair of legs, and the chela 

 may be taken as a type of this organ in the four species of the longicortte-gvouT^ represented 

 in the "Siboga" collection, as the structure is very uniform, showing only a Httle difference in 

 the length of some of the spines in various species. Thus it may be pointed out that the chelae 

 of S. instdarc differ from those in 5. longicorne mainly in having the proximal spine of the 

 penultimate joint and the two pro.ximal spines at the upper margin of the last joint somewhat 

 but not much shorter than in the last-named species, while the chelae in 5'. iiiicrophthalma n. sp. 

 are intermediate between those in S. ijisti/arc and 5. longicorne. 



Sixth abdominal segment (figs. 2 / and 2g) shorter and deeper than in the three following 

 species, being only very little longer than the fifth segment and conspicuously less than half as 

 long again as deep, with the lower margin towards the end bent rather or very suddenly upwards. 

 The exopod of the uropods (fig. 2/) broader than in the other species of this group and slightly 

 shorter than the endopod, which reaches the insertion of the large distal spines on the telson. 



The copulatory organs (figs. 2 h and 2 /) show some minor differences from those in the 

 other species of the /ongicornc-group. The spine-shaped process is somewhat long. The terminal 

 process moderately long, flattened, between three and a half times and four times as long as 

 broad, with the distal half distinctly narrower than the proximal, the inner margin somewhat 

 concave, the outer a little convex along the proximal half, the end cut olif obliquely. Proximal 

 process about as long and broad as the terminal, decreasing somewhat in breadth along its 

 proximal two-thirds, and with the distal third somewhat expanded on the inner side, the margin 

 of this expansion and the terminal margin together forming one-third of a cercle. The lateral 

 process basally somewhat removed from the proximal, somewhat shorter than and about half as 

 broad as the last-named process, with the inner margin somewhat concave, the outer somewhat 

 convex and at the broad, rounded end a little expanded on the outer side. 



Length of the male 6.5 mm., of the female 7 — 8.2 mm. 



Remarks. — This species, of which only the "Siboga" specimens are known to me, 

 is easily distinguished from the three following species of the longicorne-group by its much 

 broader antennal squama, which at least in the male reaches longer forward in proportion to 

 the joints of the antennular peduncles than in the following forms. Furthermore the two distal 

 joints in the antennular peduncles of the male are thicker and conspicuously shorter, the eyes 

 broader and the sixth abdominal segment a little deeper with the lower margin more strongly 

 curved towards the end than in the three following species, it being on the whole the most 

 clumsy form of the /o!igicor?ie-group. 



