20 G. 0. Sårs. 



Remarks. — Although only the one sex of this form is 

 known to me, I cannot doubt that it represents a distinct 

 species, well defined both from the preceding form and from 

 S. gracilis described in my first paper. As in other species 

 of the genus, it is chiefly the structure of the prehensile 

 antennæ, and more particularly of their outer hand-like 

 section, that affords the best and most easily recognizable 

 distinguishing character. This part is, indeed, rather unlike 

 that in the 2 above-named species, as it more resembles 

 that in S. vitreus, Brauer, though differing conspicuously in 

 the structural details. 



Description. 



The chief dimensions of an apparently fully grown 

 specimen are as follows: — 

 Total length, from the front to the end of the last caudal 



segment 16 mm. 



Length of head 2 — 



Length of pedigerous part 61 — 



Length of genital region 1^ — 



Length of tail proj)er 6 — 



Length of caudal rami 3 — 



Length of prehensile antennæ (fully extended) .... 7 — 



The general form of the body (see fig. 6) resembles, on 

 the whole, that of the male of the S. gracilis, though 

 perhaps somewhat less slender, the posterior division, in- 

 cluding the genital region, scarcely attaining the length of 

 the anterior, whereas in 8. gracilis it is rather longer. This 

 division, moreover, in the present species, is perfectly smooth, 

 without any trace of the knob-like prominences found in that 

 species, and the segments gradually diminish distally both in 



