138 



3. Ilyarachna denticulata, G. 0. Sars, n. sp. 



(PL LXI, fig. 1.) 



m 



Specific Characters. Very like the preceding species, both in size and ge- 

 neral appearance, but differing conspicuously in the armature of the body. Ce- 

 phalon of a similar shape to that in /. hirticeps, dorsal face densely clothed with 

 short spines. First segment of mesosome considerably smaller than the 3 suc- 

 ceeding ones, and with the lateral parts imperfectly developed; anterior edge of 

 all 4 segments divided into a regular series of from 10 to 15 very conspicuous 

 dentiform projections. The 3 posterior segments of mesosome smooth, and of a 

 similar appearance to that in I. hirticeps. Caudal segment likewise scarcely differing 

 in shape from that in the said species. Superior antennae rather short, with the 

 lusal joint strongly denticulate inside, and the 2nd joint tipped with several diverg- 

 ing spines, flagellum 8-articulate. Inferior antenna? about twice as long as the 

 body, and rather slender, penultimate joint of the peduncle without any spines 

 inside. Legs and uropoda nearly exactly as in /. hirticeps. Colour whitish. 

 Length of adult female 7 mm. 



Remarks. This form is so very like I. hirticeps both in size and general 

 appearance, as to be easily confounded with it. On a closer examination, how- 

 ever, it is distinguished pretty well by the peculiar armature of the fore- 

 body. The soft bristles clothing the dorsal face of the cephalon in the above- 

 named species, are here replaced by rigid spines, and the anterior edges of the 

 4 first segments of the mesosome are not, as in that species, finely crenulated, 

 but divided into coarse spiniform projections. On the other hand, there is no 

 trace of the strong spines occurring in 1. hirticeps on the penultimate peduncular 

 joint of the inferior antennoo. In most other respects there is a very close resem- 

 bhmce between this species and I. hirticeps. 



Occurrence. L have found this species in several places on the west coast 

 of Norway, from Stavanger up to the Trondhjem Fjord, in depths ranging from 

 100 to 400 fathoms. Off the Lofoten Islands and the Finmark coast, this species 

 ilocs not seem to occur, and it thus appears to be a more southern form. I had 

 previously confounded this species with 1. hirticeps. 



