44 



Remarks. This genus was established in the year 1873 by Messrs. Brady 

 & Robertson to comprise a small Harpacticoid, M. atlantica B. & R.. taken by 

 them in the open sea by the aid of the surface-net. The genus was subsequently 

 withdrawn by Prof. Brady, who in his Monograph described it as Ectinosoma 

 atlantieum, believing that the anatomical differences were not sufficient to remove 

 it from that genus. Dr. Giesbrecht has, however, again restored the original 

 genus, adding another nearly-related form, M. rosea (Dana). I am also myself 

 of opinion that the genus Microsetella ought to be maintained, differing, as it does, 

 from Ectinosoma, not only in the peculiar habits of the species, but also in some 

 anatomical details mentioned in the above diagnosis. Of the 2 hitherto known 

 species, only one belongs to the fauna of Norway. 



29. Mierosetella norvegiea (Boeck). 



(PI. XXIV). 



Setella norvegiea, Boeck, Oversigt over de ved Norges Kyster iagttagne Copepoder. Chr. Vid. 



Selsk. Forh. 1864, p. 281. 



Syn: Ectinosoma atlantieum, Brady. 



Specific Characters Female. Body extremely slender, nearly linear in 

 form, the greatest width scarcely exceeding Ye of the length. Cephalic segment 

 only very slightly vaulted above, seen dorsally, gradually contracted in front, 

 rostrum short and abruptly deflexed. Urosome about half the length of the an- 

 terior division of the body, segments clothed with several circlets of delicate 

 spinules. Caudal rami scarcely longer than they are broad, apical setae more or 

 less divergent, the innermost but one about twice the length of the urosome. 

 Anterior antennaB exceeding half the length of the cephalic segment, and composed 

 of 6 articulations, terminal part fully as long as the proximal one. Last pair of 

 legs with the distal joint scarcely as long as the proximal one, and rounded in 

 form, innermost apical spine very small, the other 2 considerably elongated, 

 setiform, appendicular bristle normal; inner expansion of proximal joint large, 

 extending as far as the distal joint, inner apical spine much shorter than the outer. 



Male somewhat smaller than female, and easily recognizable by the geni- 

 culate anterior antennae and the bipartite genital segment. 



Body pellucid, white, with a faint yellowish tinge. 



Length of adult female 0.46 mm., of male 0.38 mm. 



Remarks. There cannot, in my opinion, be any doubt that the form briefly 

 recorded by Boeck as Setella norvegiea is this species, arid therefore, according 



