64 



subdivided in the middle; last segment considerably larger than the preceding 

 one, with the anal operele somewhat prominent and broadly rounded at the 

 end. Caudal rami slender and narrow, though less elongated than in the other 

 known species, scarcely exceeding in length the anal segment; apical setae 

 moderately slender. Anterior antennae rather narrow, exceeding somewhat in 

 length the cephalic segment, and composed of 9 well defined joints clothed 

 with comparatively long curved setae; 2nd joint the largest and about equalling 

 in length the 2 succeeding joints combined; penultimate and antepenultimate 

 jonts very small, but distinctly defined. Posterior antennae with the outer ramus 

 narrow, biarticulate, and only provided with 2 setae. Oral parts agreeing in 

 structure with those in the other species. 1st pair of legs with the inner ramus 

 very slender, being fully twice as long as the outer; terminal joint of the latter 

 only armed with 4 spiniform setae. The 3 succeeding pairs of legs exhibiting 

 the slender form characteristic of the genus; inner ramus however com- 

 paratively shorter than in the other species, with the terminal joint less pro- 

 duced and the number of setae somewhat reduced. Last pair of legs with the 

 distal joint narrow oblong in form, and less exserted at the tip than in the 

 other species; marginal setae rather unequal in length and 5 in number; inner 

 expansjon of proximal joint comparatively broad, but only very slightly pro- 

 duced, and edged with 4 setae, the outermost one very small. 



Colour whitish grey. 



Length of abult female 0.70 mm. 



Remarks. The present form is nearly allied to the type species, S. 

 longicaudata (Scott), but is rather inferior in size, and moreover at once 

 distinguished from that species by the comparatively less elongated caudal rami. 

 In the structural details also some well-marked differences are found, as indi- 

 cated in the above diagnosis. 



Occurrence. Some few female specimen of this form were taken at 

 Riser from a depth of about 50 fathoms, muddy bottom. 



Gen. Cletomesochra, G. O. Sars, n. 



Generic Characters. Body as a rule short and stout, with the anterior 

 division more or less dilated. Cephalic segment of moderate size, and provided 

 in front with a prominent triangular rostral plate defined behind by a well- 

 marked transverse suture. Caudal rami small and widely apart. Anterior 

 antennae comparatively short and stout, being only composed of 5 joints partly 



