io 5 



Stat. 282. January 15 17. Lat. 8°2'5'.2S., long. 127° 18.4 E. Anchorage between Nusa Besi 

 and the N.E.-point of Timor. 27 — 54 m. Plankton. 1 specimen. 



Stat. 315. February 17/18. Anchorage East of Sailus Besar, Paternoster-islands. Depth up to 

 36 m. 1'lankton. 4 specimens. 



Description. The frontal plate is long, with the lateral margins very concave, the 



front margin slightly concave or straight and the surface deeply concave longitudinally (fig. ia)\ 

 the median part of the gastric area is somewhat raised as a broad, dorsally rounded keel 

 terminating in front as a narrow, low keel on the frontal plate. The eyes midde-sized, black. 

 The antennulae are èxtremely characteristic (fig. 1 6) ; the first joint is almost broader at the 

 distal than at the proximal end and distally raised as a moderately high, very oblique keel 

 running from the inner margin outwards and torwards to the front margin near the outer angle ; 

 this keel bears about 9 or 10 slender, spiniform processes projecting upwards and somewhat 

 forwards, and the outer distal angle of the joint is produced into a thicker, acute process of 

 almost the same length. The second peduncular joint has in both sexes a little from the terminal 

 margin on the outer major part of the upper side and a little downwards on the outer side a 

 cur-ved, close row of stiff seta; all converging to a point near the middle of the third joint; 

 the setae are so closely arranged that together they look nearly as a triangular lappet with the 

 base convex. The abdomen without dorsal spines; the anal spine curved and simple in both 

 sexes. The uropods with the rami subequal in length and very little shorter than the telson. 



The copulatory organs (figs. 1 c and 1 d) are mentioned in the diagnosis of the genus, 

 but some points may be added. The inner lobe (//.) is broad with the terminal margin oblique; 

 at the middle of this margin a slender, somewhat small spine is found (p 1 .), certainly representing 

 the spine-shaped process (in a single specimen I found two spines near each other (fig. 1 el), 

 but that is most probably a casual anomaly) ; near the end of the inner margin a somewhat 

 longer and stronger spine is found representing the terminal process (/>".) and a little more 

 proximally another spine intermediate in size between the two others and representing the 

 proximal process (/>*.). On the basal part of the median lobe before the insertion of the large 

 plate some tiny hooks (fig. 1 d, c) are seen, perhaps having the same unknown function as the 

 hooks on the auxiliary lobe in other genera. 



Length 8.5 — 9 mm. 



Remarks. — Sars' description and drawings of this species are imperfect as to some 

 points, and before I had seen his type I was uncertain whether my specimens really belonged 

 to his species. His type preserved in the British Museum is marked "off Port Jackson", and it 

 differs from the figures and description given by Sars and agree with the "Siboga" specimens 

 in the following main points: the existence of a denticle on the lower margin ot the carapace 

 near the end. the existence of the curious row of strong sets on the second antennular joint, 

 finally that the oblique keel with its spines at the end of first antennular joint is quite as 

 described and figured here, thus differing strongly from Sars' figs. 18 and 19. It may be added 

 that his fig. 22 is incorrect as to the relative length of the rami of the uropods and the telson 

 and does not agree with his fig. 17, on which these particulars are nearly correct. Finally, he 

 draws (figs. 22 — 23) the flat spines near the tip of the telson as being especially broad with 



ao 



S1BOGA-EXPEDITIE XXXVII. 



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