8 



end; apical setae rather strong and partly exhibiting a dense annulation. An- 

 terior antennae only slightly exceeding half the length of the cephalic segment, 

 and composed of 17 joints, the 1st of which, apparently formed by the junction 

 of the 6 or 7 proximal joints, is very large, almost occupying half the length 

 of the antenna. Posterior antennae with the terminal part (inner ramus) com- 

 paratively shorter than in P. stephoides, though a little longer than the outer 

 ramus; the latter 6-articulate, with the 2nd joint somewhat dilated, oval in 

 form, and provided outside with 3 setae, the 3 succeeding joints very small. 

 Oral parts of the structure characteristic of the genus. Natatory legs likewise 

 built on the same type as in the other species, though the rami appear some- 

 what more slender than in P. stephoides and more distinctly spinulose at the 

 end of the joints, those of 4th pair being moreover densely covered with small 

 prickles. Last pair of legs rather short and stout, with the last joint scarcely 

 longer than the middle one and somewhat hand-shaped, terminating in 3 strong 

 diverging digitiform spines of equal length, the outermost one distinctly defined 

 at the base, whereas the other 2 form the immediate continuation of the 

 joint; all 3 spines, as also partly the surface of the joint, coarsely spinulose. 



Male, as usual, smaller than female and having the urosome more 

 slender and distinelly 5-articulate. Antennae, oral parts and natatory legs 

 scarcely different from those parts in female. Last pair of legs, however, con- 

 spicuously transformed and very asymmetrical; right leg long and slender, termi- 

 nating in a somewhat flexuous point; left leg much shorter, but with the 1st 

 joint considerably tumefied, nearly globular in form, 2nd joint tapered distally 

 and provided at the end with a well-marked rudiment of an appendicular ramus, 

 3rd joint very narrow and armed at the end with a slender movable claw, 

 outside which are attached a bundle of 3 delicate and closely superposed lamellae. 



Colour of the living animal not yet ascertained. 



Length of adult female reaching to 0.90 mm., that of male to 0.79 mm. 



Remarks. The present species was first described by Mr. Wolfenden 

 from a solitary female specimen taken off the Shetland isles. Subsequently 

 T. Scott found the same species also off the Scottish coast, and has given a 

 figure with some details of a male specimen. It may easily be distinguished 

 from P. stephoides by the comparatively shorter and stouter_ form of the body 

 and more particularly by the structure of the last pair of legs in bot sexes. 

 As these appendages were somewhat damaged in the male specimen examined 

 by Scott, the figure he gives of them has turned out to be rather imperfect. 

 Moreover the right leg is described as the left, and vice versa. 



