161 



Page 28. Chiridius armatus (Boeck). 



Occurrence. A solitary male specimen, unquestionably belonging to this 

 species, was found in a plankton-sample taken during the cruise of the "Michael 

 Sars", at Stat. 10, east of Iceland, depth 250400 metres. 



Page 30. The following genus should be added: 

 GaidiUS, Giesbrecht, 1895. 



Syn: Chiridius, G. 0. Savs (part). 



Generic Characters. Body comparatively more robust than in Chiridius, 

 with the urosome shorter in proportion to the anterior division. Front produced 

 below to a very small, undivided rostral projection. Last segment of metasome 

 wholly coalesced with the preceding one, lateral lobes obtusely rounded and each 

 exhibiting, somewhat outside the tip, a narrow spiniform process pointing backwards. 

 Caudal rami short, resembling in structure those in Chin<Htt*. Anterior antennae 

 in both sexes very slender, in female 24-articulate, in male with some of the 

 articulations coalesced. Posterior antennas with the inner ramus somewhat longer 

 and narrower than in Ch'tr'nUn*. Oral parts almost exactly as in that genus. 

 Legs likewise of a very similar structure, except that in the outer ramus of 1st 

 pair, the spine outside the 1st joint is missing. 



Remarks. Although the differences between this genus and Chir/ditt* 

 appear to be very slight, it may perhaps be advisable to retain the genus, 

 since there are 2 northern species that so closely agree with that first described 

 by Dr. Giesbrecht, that the 3 species together form a natural group. The 

 typical species is G. pungens Giesbr. from the Pacific Ocean ; the other 2 species 

 have been described by the present author from Nansen's Polar Expedition as 

 Chiridms tenuispinus and C. Twevlspinu*. Both these arctic species subse- 

 quently proved to be referable to the Norwegian fauna. The female of the first- 

 named species has already been described in the present Account, and it only 

 remains here to describe the hitherto unknown male of this form. The 2nd species 

 is now for the first time added to the Norwegian fauna. 



22 Crustacea. 



