184 



121. Stenhelia aemula (Scott). 

 (PI. cxxi). 



Delavalia cemula, Scott, Additions to the Fauna of the Firth of Forth; Eleventh Report of the 

 Fishery Board for Scotland, p. 204, PI. IV, figs. 3647. 



Specific Characters. Female. Body of the usual short pyriform shape, 

 being perhaps still more robust than in the 2 preceding species. Rostrum some- 

 what more attenuated, with the tip transversely truncated. Caudal rami a little 

 longer than the anal segment, and slightly tapered distally. Antennae and oral 

 parts scarcely different from those in the typical species. 1st pair of legs with 

 the outer ramus about as in that species, the last joint being somewhat shorter 

 than the middle one, which is without any seta inside; inner ramus longer than 

 the outer, and distinctly 3-articulate, 1st joint, however, much shorter than in the 

 2 preceding species, being scarcely longer than the other 2 combined, the latter 

 not bent upon the former, and of about equal size. Natatory legs very strongly 

 built, with the 1st joint of the inner ramus considerably dilated, and in 4th pair 

 carrying inside an unusually strong deflexed seta. Last pair of legs with the 

 distal joint spatulate in form, the tip being obtusely blunted, marginal setse rather 

 slender, none of them spiniform; inner expansion of proximal joint very slight, 

 and carrying 4 slender ciliated setae, the outermost shorter than the other 3. 

 Ovisacs not very large, and containing a limited number of ova. 



Colour not yet ascertained. 



Length of adult female 0.50 mm. 



Remarks. The above-described form is unquestionably that recorded by 

 Th. Scott as Delavalia cemula, though somewhat inferior in size. It is chiefly 

 characterised by the structure of the inner ramus of the 1st pair of legs, which, 

 though distinctly triarticulate, as in the 2 preceding species, is scarcely at all 

 prehensile, a character which gives it a place between those two and the suc- 

 ceeding species. Th. Scott has also examined the male of this species, and gives 

 a figure of the 2nd pair of legs, the inner ramus of which appears to be trans- 

 formed in much the same manner as in the 2 preceding species. 



Occurrence. Only some few specimens of this form, all of the female 

 sex, have hitherto come under my notice. They were taken last summer off the 

 south coast of Norway, at Flekkero and Farsund. 



Distribution. Scottish coast (Scott). 



