398 



body. Anterior antennae long and slender, fully twice as long as the cephalic 

 segment, and clothed in their outer part with unusually long and slender setae, 

 2nd joint the largest, 3rd joint longer than 4th, terminal part scarcely attaining the 

 length of those two joints combined. Posterior antennae likewise more slender than 

 usual, outer ramus distinctly biarticulate, terminal joint very small. Mandibular 

 palp, as in the other species, simple, biarticulate, basal joint however carrying 

 inside, in place of the usual setae, a single remarkably strong spiniform appendage 

 minutely denticulated at the end 1 ), distal joint comparatively small. 1st pair of 

 legs rather slender, outer ramus a little shorter than the 1st joint of the inner, 

 and having its 3 joints of about equal length, last joint of inner ramus fully twice 

 as long as the middle one, both together about half the length of the 1st. The 

 3 succeeding pairs of legs with the rami slender and narrow, setae present in the 

 normal number. Last pair of legs with the distal joint comparatively small, oblong 

 oval in form, slightly tapered, and carrying 5 rather unequal setae, that issuing 

 from the tip very long and slender; inner expansion of proximal joint obtusely 

 rounded at the end, and extending beyond the middle of the distal joint, marginal 

 setae 4 in number and rather strong, the outermost but one the longest. 



Colour whitish, pellucid. 



Length of adult female 0.70 mm. 



Remarks. The above-described form is undoubtedly that originally recorded 

 by Th. Scott as A. tenuicornis, and is very different from the species so named in the 

 principal part of this account. On the other hand, it has a general resemblance 

 to A. attenuate* Thompson, exhibiting a similar very slender form of body. It 

 is however of considerably larger size, and moreover easily distinguished by the 

 comparatively shorter caudal rami and the very different form of the last pair of 

 legs. The extraordinary length of the caudal setae in the present species has quite 

 escaped the attention of Th. Scott, probably because those setae had accidentally 

 been broken off in the specimen examined by him. 



Occurrence. Several specimens of this form were found last summer at 

 Korshavn in a single locality, which also yielded many other interesting Copepoda, 

 most of them of a remarkably slender form of body. Some of these have already 

 been described in the preceding pages, and several others will be treated of 

 below. The locality was a submarine bank with coarse sandy bottom and 

 located at some distance outside the village at a depth of 30 to 40 fathoms. 



Distribution. Scottish coast (Scott). 





and 



l ) This appendage was erroneously considered by Th. Scott to be a particular ramus, 

 and the palp of course described as biramous. 



