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segment large, though scarcely occupying half the total length, and only slightly 

 contracted anteriorly, frontal crest only faintly indicated, postero-lateral corners 

 of the segment fairly prominent. Epimeral lappets of the 3 succeeding seg- 

 ments moderately produced; those of penultimate segment rather smaller than 

 the preceding ones. Tail comparatively more produced than in the other species, 

 attaining nearly half the length of the anterior division; genital segment not 

 much expanded in its anterior part; anal segment scarcely as long as the 2 

 preceding ones combined. Caudal rami about twice as long as they are broad, 

 and slightly dilated in the middle; outermost seta rather far from the apex and 

 much shorter than the innermost, the 2 middle setse of moderate length. Anterior 

 antennae unusually slender and elongated, considerably exceeding half the length 

 of the cephalic segment, and composed of 12 well-defined joints, the last of 

 which is the longest. Posterior antennae likewise rather slender, with the ter- 

 minal joint nearly twice as long as the penultimate one. Siphon moderately 

 produced, extending about to the insertion of the 1st pair of legs. Maxillee with 

 the lobes not very unequal; apical seta of the inner one quite short, those of 

 the outer very coarse, spiniform and densely spinulose. Maxillipeds resembling 

 in structure those in B. major, the dactylus of the anterior ones being very 

 slender, with only a single small thumb-like process at some distance from the 

 end, terminal claw much curved, secondary spine small. Natatory legs rather 

 strongly built, with the exterior edge of the outer ramus coarsely serrate; inner 

 ramus of 4th pair not much shorter than the outer, but rather narrower. Free 

 joint of last pair of legs somewhat more produced than in the other species. 



Colour reddish brown. 



Length of adult female reaching to 2.90 mm. 



Male unknown. 1 ) 



Remarks. This form grows to a still larger size than B. major, and is 

 indeed the largest of all the siphonostomous Cyclopoida with which I am acquainted. 

 It moreover exhibits several well-marked differences from the other species, both 

 as to its outward appearance and the structural details. The specific name 

 alludes to the unusually produced tail. 



Occurrence. 2 female specimens only of this form have come under my 

 notice. They were taken, many years ago, at Tj0t0 on the Nordland coast, from 

 the considerable depth of 150 fathoms 



l ) It may be, however, that the male specimen mentioned above as belonging to B. major, 

 should more properly be referred to the present species, though it was found in company with 

 the former. Indeed, on a closer examination, I have found that the caudal rami in that specimen, 

 as also the mutual relations of the joints in the inner ramus of the 4th pair of legs, agree better 

 with the present species. 

 17 Crustacea. 



