NO. 6.] ACCOUNT OF THE SPECIES. 75 



Occurrence. This small Calanoid occurred in considerable numbers in 

 the samples taken north of the New Siberian Islands, in October, 1893; no 

 male specimen, however, was found. 



Gen. Spinocalanus, Giesbrecht. 



Remarks. This genus was established by Dr. Giesbrecht, to include a 

 small Calanoid found in the tropical part of the Pacific Ocean, at a very 

 considerable depth (1000 — 4000 metres), for which reason the species was 

 named S. dbyssalis. As the specimens were in a somewhat imperfect state 

 of preservation, only some few detail-figures were given, to show the more 

 important anatomical characters. On comparing these figures with those of 

 a small Calanoid from the Nansen Expedition, I find so close a resemblance, 

 that I am induced to refer this form to the same genus. The characteristic 

 structure of the maxillipeds in particular, is the very same in the two forms ; 

 and the dense clothing of spinules on the natatory legs also, from which the 

 generic name has been derived, is found to be very distinct at least on the 

 inner ramus. The total absence of any rostral prominence or frontal appen- 

 dages is likewise a character common to both forms. 



15. Spinocalanus longicornis, n. sp. 

 (PL XXII). 



Specific Characters. Body in both sexes comparatively short and thick, 

 though rather different as regards the relative length of the 2 chief divisions. 

 Cephalic segment not distinctly defined from the 1st pedigerous one, and 

 somewhat applanated anteriorly, front quite simple, without the slightest trace 

 of rostral prominence or tentacular filaments. Last 2 segments of trunk 

 coalesced, lateral corners rounded off. Tail in female not even attaining Vs 

 of the length of the anterior division, in male considerably more slender and 

 elongated. Caudal rami comparatively short, each with 4 apical setae. Ante- 

 rior antennae considerably exceeding in length the whole body, in female 23- 

 articulate, 7th articulation, especially in the male, very much elongated. Pos- 

 terior maxillipeds very slender, with the terminal part almost twice as long 

 as the 2nd basal joint, and clothed with very long and coarsely ciliated setae. 

 Natatory legs slender, inner ramus in the 3 posterior pairs armed behind 



