79 



segment about the length of the 3 succeeding segments combined and broadly 

 rounded in front; rostral projection rather prominent, and terminating in an 

 acute somewhat recurved point. Last trunkal segment comparatively large and 

 tumid. Urosome not fully attaining the length of the anterior division; genital 

 segment fully as long as the 2 succeeding segments combined, and distinctly 

 subdivided in the middle; last segment exceeding in length the preceding one 

 and conspicuously contracted distally. Caudal rami rather slender and narrow, 

 about half the length of the remaining part of the tail; outer edge with 2 

 successive small bristles in its anterior half; dorsal seta issuing at the end of 

 the first Vs of the ramus; apical seta rather slender. Anterior antennae com- 

 paratively short and stout, scarcely exceeding half the length of the cephalic 

 segment; 2nd joint much the largest, being nearly twice as long as the 3rd. 

 Posterior antennae rather strongly built, with the terminal joint considerably 

 dilated at the end, innermost apical seta remarkably strong and cloted on the 

 outer edge with long cilia; outer ramus more fully developed than in the 

 other species and provided with 3 marginal setae. Oral parts normal. Natatory 

 legs likewise built in the usual manner, though comparatively rather small; 

 outer ramus in all of them without any setae inside. Last pair of legs very 

 peculiar and unlike those in any of the other known species; proximal joint 

 without any bristle-bearing process outside, its inner part considerably expanded 

 and highly chitinised carrying inside 2 successive spiniform setae and produced 

 at the end to a long mucroniform process denticulated in its outer part and 

 pointing obliquely backwards and outwards; distal joint very small and im- 

 perfectly defined at the base, with 3 comparatively short setae. 



Male of about same size as female and very like it in its general 

 appearance, though easily recognisable by the distinctly hinged anterior 

 antennae. Last pair of legs scarcely different from those in female. 



Colour pale whitish grey. 



Length of adult female 0.55 mm. 



Remarks. The highly remarkable structure of the last pair of legs is 

 sufficient for at once distinguishing the present form from any of the other 

 known species. In the other structural details it shows itself however to be 

 a true member of the present genus. 



Occurrence. Two specimens only of this form, a female and a male, 

 have as yet come under my notice. They were found last summer (1918) at 

 Hvalar, outside the Christiania Fjord, in a depth of about 6 fathoms, 

 muddy bottom. 



Distribution. Scottish coast (Scott). 



