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The inner side of eacli segment has a transverse row of more delicate spines or hairs and 

 these form tufts of hairs at the concave side, especially of the lower segments. 



Third cirrus of the right side with both rami much shorter than those of the left side. 

 The rami of the third cirrus of the left side have ii and 9 segments: form of the segments 

 and distribution of the spines much like in the second cirrus. 



Fourth cirrus of the right side quite rudimentary, rami very unequal, both composed of 

 five seo-ments, with small groups of hairs at the extremity of the segments. On the left side 

 the cirrus is composed of two nearly equal rami composed of 1 1 segments. The fourth left 

 cirrus has the same structure as the left one of the fifth pair (PI. I, fig. 20): the groups of 

 spines on the dorsal side of the rami at the extremity of the segments and growing stronger 

 in the terminal segments are very characteristic for both cirri. 



The right-hand cirrus of the fifth pair is extremely small, rudimentary (PI. I, fig. 2 i). It difters 

 from that of the fourth pair in having quite equal rami. They are composed of five segments. 



Both cirri of the sixth pair have a stronger ramus of 1 2 broader segments and a more 

 slender ramus of 1 1 segments. The\ bear, at the extremity of the segments towards the dorsal 

 side, the same groups of stronger spines as in the left-hand cirrus of the 4''' and 5'*^ pair: at the 

 anterior or concave side, each segment bears as a rule one pair of spines or a larger spine 

 accompanied by two or three more slender ones. 



Caudal appendages (PI. I, fig. 22) shorter than the first segment of the pedicel 

 of the sixth cirrus, slender with a dense tuft of hairs near the extremity and a few hairs along 

 the sides. 



Penis cylindrical, growing thinner towards the extremity, with very numerous and very 

 delicate curved hairs scattered over its surface ; a tuft of such hairs at the extremity. 



Eggs numerous, long oval. Longest axis 0,2 to 0,22 mm., shortest axis 0,08 mm. 



This species was taken in half a dozen specimens, only two of which seem to be 

 full-grown, at : 



Stat. 253. December 10, 1899. Lat. 5°4S'.2 S., Long. 13.2° 13' E. Depth 304 m. Bottom: gray 



clay, hard and crumbly. 

 Stat. 251. December 8, 1899. Lat. 5^28'.4S., Long. i32°o'.2E. Depth 204 m. Bottom: hard 



coral sand. One small specimen. 



General Remark. This is a very remarkable species. Were it not for Darwix's 

 (Hinds') P. eburneum^ 1 would have felt greatly inclined to consider it as representing a new 

 genus. As already observed b)- Hinds (who therefore proposed the name TrilasDiis for this 

 Cirri ped) and as described in detail by Darwin, the terga are "entirely" absent in P. cbiti-ncnni 

 and at first I did not find them in P. obliqiium either. Yet on studying the capitulum more 

 carefully, I discovered the terga as extremely minute triangular pieces, hidden in the folds of 

 the membrane uniting the two scuta over the upper end of the carina. In this regard the new 

 species obliqimm with its quite rudimentar\- terga bridges the cleft which separates P. crasstivi 

 with small (Darwin says "rudimentary" terga — but they are well-developed and even large 

 in comparison with those of P. obliqnnDi) terga and P. cbitrncitDi with no terga whatever. 

 The structure of the parts composing the mouth in P. obliquinn difters in several regards 



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