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edge slightly convex and carrying in the middle a slender seta. 1st pair of legs 

 with the outer ramus much shorter than the inner, spine of the middle joint at- 

 tached close to the end, apical claws rather slender and gradually increasing in 

 length inwards, inner ramus with the proximal joint very narrow and elongated, 

 seta of the inner edge attached far in front of the middle, distal joint very small 

 and slightly expanded outside, apical claws of moderate size, the inner one twice 

 as long as the outer. Natatory legs with the terminal joint of the outer ramus 

 fully as long as the other 2 combined, and of narrow linear form, setae of the 

 inner edge in both rami much reduced in number. Last pair of legs with the 

 distal joint oblong hastate in form, densely spinulose on the edges, and provided 

 with 8 marginal setae, 3 of which issue from the inner edge; inner expansion of 

 proximal joint triangular and not nearly extending to the middle of the distal one. 



Mule considerably smaller than female, and having the inner ramus of 

 3rd pair of legs (not that of 2nd pair) transformed, the terminal joint being pro- 

 duced at the tip to a long mucroniform spine. Last pair of legs very small, 

 with the distal joint subdivided into 2 or 3 successive segments. 



Colour pale yellow. 



Length of adult female 0.58 mm. 



Remarks. This form was first described by Glaus from the Mediterranean, 

 at Messina, and has subsequently been found to occur also in the northern oceans. 

 The Thalestris Jcarmensis of Boeck is unquestionably identical with Claus's species, 

 and the form recorded by Th. Scott under the name of T. for/indoides has also 

 proved to be the same species. By its slender cylindrical and very flexible body 

 this form (lifters conspicuously from the other Thalestridae, and so far exhibits 

 a pronounced similarity to certain forms belonging to the family Cawthocamptidce. 



Occurrence. I have met with this form not unfrequently in several places 

 both on the south and west coasts of Norway, as also in the Trondhjem Fjord, 

 in the littoral region among algae. On account of its small si/e and inconspicuous 

 colour, it is, however, easily overlooked. 



Disti-Hi/itiun. Mediterranean (Glaus), British Isles (Scott), ? Gulf of Guinea 

 (same author), coast of Bohusliln (coll. Gleve), Spitsbergen (Scott), Franz Josef 

 Land (do.). Polar Islands north of Giinnell Land (2nd Fram Kxped.). 



