104 



Nephr. Tkomsoni four other spinules stand on the posterior margin of the hepatic sulcus 

 (C. Spence Bate, 1. c. p. 1S6, PI. XXVI, fig. i), in Nephr. Siöogae, however, these four 

 spinules are wanting altogether, the posterior margin presenting even no tracé of 

 them. Unfortunately Spence Bate, when indicating (1. c. p. 191) the differences between the 

 female specimens and the male, collected by the "Challenger", makes no mention of these 

 four spinules, so that it remains uncertain whether they exist also in Nephr. Ckallengeri or not. 



Between the small spine at the upper end of the hepatic groove and the frontal margin 

 there are usually, like in the "Challenger" female {Nephr. Challengeri), three small spines ; the 

 foremost one, just behind the orbital margin, is situated a little nearer to the antennal spine 

 than to the large first post-rostral spine and is very small, as small as the 4 th post-rostral spine ; 

 the 2 nd , which is still smaller than the foremost one, is placed one and a half as far distant 

 from the antennal spine as from the post-rostral ridge, the 3 ld spine, finally, a little larger than 

 the i st or foremost, is situated, in a line uniting the 2 nd spinule with that at the upper end of 

 the hepatic groove, about twice as far distant from this spine as from the 2 nd spinule. Sometimes 

 the 2 nd spinule, the smallest of the three, is not developed at all : in one male and in one 

 female it is wanting on each side of the carapace, in two males and in one female on one side, 

 either the right or the left. 



Cervical groove deep and hairy. The cardiac and branchial regions fully agree with 

 those of Nephr. Tkomsoni and therefore differ from those of Nephr. Challengeri. The cardiac 

 region is traversed in the middle line by a prominent ridge; at the anterior end of this ridge 

 there is a pair of anteriorly-directed spines, that have the same size as the penultimate pair 

 of post-rostral spines and, posterior to these spines, the ridge carries on each side 6 or 7 spinules, 

 in pairs, usually sharp, sometimes, however, partly worn off, though never wanting altogether. 

 On each side of the median ridge the carapace is traversed by three obtuse and little prominent 

 carinae, arranged and running like in Nephr. Tkomsoni and also defined anteriorly by a small 

 spinule. In the largest male and in a very large female there are two small spinules instead 

 of one at the anterior extremity of the left submedian carina, abnormal of course. The lateral 

 or inferior carina, which, beginning near the postero-lateral angle of the carapace, graduallv 

 diverges from the lower margin, is a little closer and a little more coarsely granulated than 

 the surrounding parts of the upper surface, but this is not the case with the other carinae. 

 The carapace appears almost smooth to the naked eye, but, when examined under a lens, one 

 observes a fine granulation, especially on the branchial regions, while the cardiac region is 

 marked moreover with transverse rugosities and posteriorly the median ridge is even united 

 with the submedian carinae by two low transverse elevations on each side. The carapace 

 presents also a fine pubescence. The cardiac and branchial regions are, like in Nephr. Tkomsoni, 

 separated by a deep groove from the broad, flattened and finely punctate, though not granulate 

 band that borders the posterior margin of the carapace and that is traversed by the median 

 cardiac ridge. 



As regards the general shape of the abdomen (PI. IV, fig. iS and 18 a) Nephr . Sibogae 

 resembles the two species collected by the "Challenger". In all the specimens, however, taken 

 by the "Siboga" the 2 nd — 5" 1 terga appear smooth and shining to the naked eye; the 



