68 G- O. Sars. 



rowly rounded frontal part, whereas posteriorly it is but 

 slightly attenuated. As in other species, this division exhi- 

 bits 6 well-defined segments, the 1st of which is much the 

 largest, equalling in length the 4 succeeding segments com- 

 bined. At the sides of this segment, the 2 pairs of antennæ 

 and to some extent also some of the oral parts are seen 

 to project. The last segment is deeply emarginated in the 

 middle, and is produced on each side of the emargination 

 to a lamellar expansion pointing backwards and extending 

 somewhat beyond the 1st caudal segment. As in B. triarti- 

 culata, these expansions are each divided into 2 lobes, the 

 outer of which is much the larger and of broadly lanceolate 

 form, terminating in a sharp point, bent slightly outwards. 

 The inner lobe is extremely small, appearing merely as a 

 slight acute lappet issuing from the inner side of the outer 

 lobe. In B. triarticulata these inner lobes are much more 

 fully developed, and the outer lobes rather narrow, mucro- 

 niform, and considerably divergent. 



The tail is comparatively short, not nearly attaining 

 half the length of the anterior division, and, as usual, is 

 much narrower. It is divided into 3 well-defined segments, 

 the 1st of which, the genital segment, is much the largest, 

 and somewhat irregularly dilated in the middle, exhibiting 

 below a rounded prominence, to which the egg-bag, when 

 present, is attached. The last segment, which about equals 

 in size the penultimate one, is somewhat dilated distally, 

 and exhibits at its end the anal opening, partly covered 

 above by a semilunar ridge. To this segment the caudal 

 lamellæ are attached. They are comparatively larger than 

 in B. triarticulata, attaining about the length of the last 2 

 segments combined, but otherwise they exhibit much the same 

 appearance, having each 5 strong and densely plumose 



