Occurrence. I have met with this form occasionally in several places of 

 the west coast of Norway, for instance at Kopervik, Aalesund and Christiansuncl, 

 in the littoral region among alga3. It is, however, not nearly so common as the 

 2 preceding species. 



Distribution. British Isles (Brady). 



73. Parathalestris Jacksoni (Scott). 



(PI. LXIX). 



Thalcstris Jacksoni, Th. Scott, Report on marine and fresh water Crustacea from Franz Josef 

 Land, Linn. Soc. Jonrn. Vol. XXVII, p. 109, PI. 8, figs. 39. 



Specific Characters. Female. Body elongated, but rather strongly built, 

 with highly chitinized integuments and the segments very sharply marked off from 

 each other. Cephalic segment about the length of the 4 succeeding segments 

 combined, epimeral parts evenly curved, posterior edge, like that of the 3 suc- 

 ceeding segments, minutely crenulated; rostrum short and blunt, well defined at 

 the base, tip minutely bifid. Urosome slender tapering distally, genital segment 

 very distinctly divided in the middle. Caudal rami unusually prolonged, being 

 more than twice as long as they are broad and slightly attenuated distally, apical 

 setae normal. Anterior antennae of moderate length, with the distal part scarcely 

 half as long as the proximal one. Anterior maxillipeds rather compact, with the 

 claw of the outermost lobe unusually short. Posterior maxillipeds powerfully de- 

 veloped, hand large, oval fusiform, with the palmar edge slightly concaved. 1st 

 pair of legs moderately strong, outer ramus fully as long as the inner, 2 of the 

 apical claws very strong and curved; apical claws of inner ramus very unequal, 

 the inner one more than 3 times as long as the outer. Last pair of legs well 

 developed, foliaceous, distal joint very large, ovate, inner expansion of proximal 

 joint scarcely extending beyond the middle of the distal one, marginal setae of 

 moderate length. 



Male exhibiting the usual sexual differences. 



Colour yellowish brown, somewhat darker at the end of the segments, 

 dorsal face of cephalic segment of a lighter hue. 



Length of adult female 2.20 mm. 



Remarks. This form was first described by Th. Scott from Franz Josef 

 Land. It is one of the largest Harpacticoida, and by its strongly built body, 

 the sharp demarcation of the segments, and the unusually prolonged caudal rami, 

 somewhat resembles certain species of the genus Thalestris (in the restriction here 



