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much reduced in size. Anterior antennae comparatively shorter than in that 

 species, scarcely attaining the length of the cephalon, but having some of the 

 setae rather longer; 1st joint less broad; 2nd somewhat longer than the 2 suc- 

 ceeding joints combined, and slightly curved; 4th joint about the length of the 

 5th, which equals in length the 2 outer joints combined. Posterior antennae 

 shorter and stouter than in L. albens, with the 2nd joint rather thick and 

 not attaining the length of the 2 outer joints combined; apical claws 2 in 

 number, both rather strong, the outer one being much the longer. Max- 

 illae with the terminal lappet abruptly bent at the base and edged with rather 

 long cilia, especially at the basal curvature; palp with a small additional seta 

 inside the other 2. Anterior maxillipeds with none of the spinules of the 

 apical lash particularly strong. Natatory legs on the whole resembling in 

 structure those in the type species; spines of outer ramus in 1st pair however 

 broadly marginate, dagger-shaped. Inner ramus of 4th pair of legs scarcely 

 longer than the first 2 joints of the outer combined; distal joint oblong oval 

 in form, with the inner edge evenly curved, apical spines comparatively short, 

 the outer one scarcely half as long as the inner. Last pair of legs with the 

 free joint small, though a little more produced than in L. albe/is, and slightly 

 curved. Ovisacs oblong oval in form and extending scarcely as far as the 

 caudal rami. 



Male exhibiting the usual sexual differences from the female. 



Colour whitish, pellucid. 



Length of adult female amounting to 1.40 mm.; that of male to 

 about 1 mm. 



Remarks. This form is at once recognised by the very slender tail, 

 the elongate anal segment, and the peculiar structure ot the caudal rami. 

 It also differs conspicuously from L. albens in some of the structural details, 

 and more particularly in the form and armature of the posterior antennae. 



Occurrence. I have taken this form not unfrequently from the bran- 

 chial cavity of Ascidia mentula and canina captured in different places on the 

 south and west coasts of Norway. Thorell obtained it only from the last- 

 named Ascidian. 



Distribution. Bohuslan (Thorell), British Isles (Brady). 



