NORTH ATLANTIC SEA AND THE FAROE CHANNEL. 131 



Chiridius. In 1892 Giesbrecht established this genus for a Copepod 

 {Ch. poppei) of small size (1'8 mm.), which was characterised by the 

 absence of rostrum and the very short endopodites of posterior antennae 

 and mandible. 



Sars has extended the genus by the inclusion of four species — Ch. 

 armata, Ch. h-evispinus, Ch. tenuispinus, and Ch. ohtusifrons. There 

 can, however, be no doubt that hrevispimts and tenuispinus are really 

 examples of Giesbrecht's genus Gaidius. In both occur the modified 

 tubal bristles of the basal joint of the fourth feet, which Giesbrecht re- 

 marked long ago to be midway between the ordinary bristles of ^tideus 

 and the spines and teeth of Euchirella. Chiridius teimispinus (Sars) 

 is identical with Gaidius horecdis (described by me in this Journal, 

 January, 1902), and Chiridius brcvispinus (Sars) is identical with the 

 species which I had previously named Gaidius major. 



Chiridius armatus (Sars), owing to its possession of a two-pointed 

 rostrum, is clearly not a Chiridius, and from its close resemblance to 

 u^tideiLs was, two years ago, placed by me in another genus to which 

 I gave the name Pseudmtidcus. (See Report of the Brit. Assoc., the 

 Zoological Station at Naples, 1902.) 



Consequently only one of Sars' species, viz. Chiridius ohtusifrons 

 remains to be included in the genus Chiridius, which now includes 

 only CJi. poppci (Gbt.) and Ch. ohtusifrons (Sars). The latter form, 

 which appears to have been abundant in the Polar basin in Nansen's 

 Expedition (Sars, loc. cit.), occurs also, though not commonly, in the 

 Faroe Channel, and my examples agree entirely with the description 

 given by Sars. 



It may be doubted if the Gaidius pungens of Giesbrecht is really 

 identical with the Faroe Channel and North Atlantic forms, for in the 

 former the second pair of feet have a one-jointed endopodite, while in 

 the latter it is distinctly two-jointed, added to which must be considered 

 the widely different localities of habitat, which would at once lead to 

 a supposition of non-identity. (PI. IX., tig. 43.) 



G. 2)ungens (Giesbrecht). 



Exopodite of first foot two segments. 

 Endopodite of second foot one segment. 

 Spiny prolongation of last segment shorter than in horealis. 

 Size, 9 3-2 mm. (Pacific Ocean). 



G. horealis (Wolfenden), Ch. tenuispinus and G. tenuispinus (Sars). 

 Exopodite of first foot indistinctly three segments. 

 Endopodite of second foot two segments. 

 Spiny prolongation of last segment longer than pwujens. 

 Size, ? 3-8 mm. (North Atlantic). 



