28 



According to Col. Alcock's description, wliose specimens were taken in the Andaman 

 Sea, the pleurobranchiae in advance of somite XIV' should be distinct filaments, some of which 

 are providcd with ihree or four tiny pinnules. In the specimens collected by the "Siboga", these 

 pinnules are more numerous and they are for the majority l>ifii,rcate : their number, however, 

 is somewhat variable. 



The lo specimens from Stat. 38 are all young and nearly of the same size, the carapace, 

 rostrum excluded, being 26 — 28 mm. long. As was already pointed out by \V(iod-Mason, the 

 rostrum of these voung males ends in a long styliform process, that is somewhat curved upward 

 and that reaches far beyond the antennular peduncles. So in two males, in which the carapace 

 is 27 mm. long without the ro.strum and 48 mm. when it is inclucled, the styliform rostrum 

 reaches to the distal spine at the outer margin of the antennal scales, in another male of the 

 same size it extends to the end of the scaphocerites and in a fourth even beyond them. In the 

 voung females the rostrum is as long or slightly longer than the carapace, extending far beyond 

 the antennal scales. At this age the inner antennular flagellum does not yet show, in the male, 

 the curious bend and twist at the base, that is observed in the adult. At this age also, in the 

 male, the antero-external angle of the propodus of the external maxillipeds is not yet prolonged 

 beyond the articulation of the dactylus and the branches of the petasma are not yet united 

 with one another. In a male, long 115 mm., with styliform rostrum, the pleurobranchia of 

 somite XIII is 1,7 mm. long and bears at each side 14 or 15 for a part already bifurcate pinnules. 



The specimens from Stat. 74 are almost adult and agree with Alcock's description, 

 except that in the females the external maxillipeds are not shorter but even slightly longer 

 than the 1*' pair of legs, so e. g. in a female long 160 mm. The antennal flagellum of this 

 female is 260 mm. long, more than one and a half as long as the body. In a male, long 

 140 mm., the pleurobranchia of Somite XIII is i,Smm. long with 14 or 15 pairs of pinnules, 

 of which the 8 or 9 proximal ones are bifurcate ; in a female of the same size this gill has the 

 same length, but there are only 10 or 11 pairs of pinnules, that are a little longer than in 

 the male; in another female, long 170 mm., the pleurobranchia of Somite XIII is 2 mm. long 

 and bears 11 or 12 partly bifurcate pinnules that are again as long as in the male. 



The male from Stat. 161 is adult, the carapace with the rostrum being 51 mm. long; 

 the rostrum that measures Y,, the length of the rest of the carapace, reaches to the end ot the 

 2"'' antennular article ; it is not horizontal as usual, but obliquely directed upward. The two 

 females are also adult, nearly of equal size, 190 mm. long. In one of them the rostrum is 

 little more than half as long as the rest of the carapace, it reaches to midway between the 

 tip of the antennular peduncle and that of the antennal scales and is slightly turned 

 downward; in the other female the rostrum reaches just beyond the extremity of the 

 antennular peduncle and its styliform, distal half is slightly curved upward; in the first 

 female the external maxillipeds are a little shorter than the i'^' pair of legs, in the other they 

 are just as long. In these females the pleurobranchia of Somite XIII is 2,4 mm. long and 

 bears 11 or 12 pairs of pinnules, most of which are bifurcate. 



The female from Stat. 173 is 140 mm, long; the pleurobranchia of Somite XIII is a 

 filament long 2,3 mm. with 15 pairs of pinnules, that are for the greater part bifurcate. 



28 



