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The same is the case with the ridges along the roof of the carina : these ridges are 

 by no means so distinct in tTie "Siboga" specimens as in that of the "Challenger". I should 

 mention also that the scales of the peduncle which in the "Challenger" specimen are placed 

 in not very regular rows, in the largest "Siboga" specimen may be said to form longitudinal 

 rows; in the smaller specimen, however, this can hardly be said. 



With regard to the shape of the carina I found that this species belongs also to the 

 Sectio C : the umbo of the carina is not tjuite at the apex of the valve, but at a short distance 

 from it. In this regard it much resembles Sc. polymorphum with which it corresponds also in 

 several other regards. 



Finally I must point out, that the chitinous interspaces between the valves which were 

 rather broad in the "Challenger" specimen, are much more prominent in the larger "Siboga" 

 specimen (from Station 175) than in the smaller (the one figured) which was taken at Station 208. 



The structure of the animal of the only specimen taken by the "Challenger" was not 

 studied; I have thought it useful, therefore, to examine one of the "Siboga" specimens. 



Mouth not very bullate ; crest of the 1 a b r u m with a row of very small knobs at the 

 place of the teeth; palpi conical, rather small, with a group of short bristles at the tip and 

 a couple of very short spines on the internal margin about the middle of its length. 



Mandibles with three teeth ; distance between i and 2 slightly greater than that 

 between 2 and 3 ; inferior angle close to tooth 3, short, rounded and delicately pectinated. 

 Short hairs are planted along the under margin. 



Maxillae with a not verv distinct notch about or a little above the middle of the edo:e; 

 above the notch three unequal spines, in the notch (or as fourth spine above the notch) one 

 spine; beneath the notch six spines. Apodeme stout, rather long and broader at the extremity. 



Outer maxillae rounded, with the bristles divided into two separate tufts ; the orifice 

 giving entrance to the body cavity at the end of a long and flat process, transversely cut oft" 

 at the extremity. 



Cirri. First pair short, not separated from the second by an interspace; rami unequal 

 in thickness and slightly in length; the shorter ramus has about 8 broad, the longer 10 more 

 cylindrical segments. The first segment in both rami is much longer than the others, the last 

 one considerably shorter. In both i-ami the segments are thickly clothed with spines. 



Second cirrus (in the specimen investigated) both rami broken off at one side, and one 

 ramus broken off at the other side. The only remaining ramus has i 7 segments, the first of which 

 is rather long, the following nearly quadrilateral, the last ones cylindrical and much narrower. 



Sixth cirrus has 22 segments in both rami: the first one very long, then come four 

 or five nearly quadrangular segments, the following nine growing longer and narrower, the 

 1 4'h being the longest of all and nearly five times as long as broad. The la.st segments grow 

 still narrower but diminish in length : the last is very narrow and tapers towards the extremity, 

 where three short spines are planted. The number of pairs of spines found on the front side 

 of each .segment is from three to seven; this number is largest at the 14"'' segment. 



Caudal appendages long and narrow, tapering towards the extremity and consisting 

 of 5 (left side) or 6 (right side) segments, of which the penultimate is the longest. Near the 



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