COPEPODA. 13 



RHINCALANUS (Dana). 

 (Plate II., fig. 6.) 



Rhine, grandis, Giesbrecht, 'Belgica' Eep., p. 18. 

 ? Rh. gigas, Brady, ' Challenger ' Rep. XIX., p. 42. 



„ Scott, 19tli Eep. Scotch Fishery Board (1901), p. 237. 



„ Giesbrecht, Fauna u. Fl. Feap. XIX. (1892), p. 153. 



Rh. gigas was described by Brady as distributed over a very wide area between 

 long. 53° 32' W.— 130° 52' E. and lat. 36° 44' S —65° 42' S. Much doubt has been 

 expressed by Giesbrecht as to the validity of this species, and the figures given by 

 Brady of abdomen and of the whole animal are those, in Giesbrecht's opinion, of 

 immature animals, and this author thinks that Brady's figure of the first feet is really 

 of one of the other pairs of feet. 



Scott's specimens (Fair Isle and Firth of Forth) are regarded by Giesbrecht as 

 Bh. nasutus ( Th. 3 and 4 with dorsal or with a lateral spine, as in nasutus, and a pair of 

 small dorsal points on the genital segment). Mobius's specimen from the north of 

 Scotland is also identical with nasutus. Rh. nasutus is very common in the Faroe 

 Channel and seas off the north of Scotland, and occurs abundantly in my collections 

 made in these regions and along the Atlantic trough, west of Ireland, and also 

 appears in the ' Gauss ' collections as far south as lat. 20° N., while in the same 

 collections Rh. grandis (Giesbrecht) appeared. From the remarks of Sars in 

 "Crustacea of Norway," Vol. IV., p. 15, it might be inferred that Rh. nasutus is of 

 rare occurrence in the Northern Ocean (" two specimens were taken east of Iceland, 

 one specimen by Hjort between Scotland and Norway, and it has not yet been found 

 in the immediate vicinity of the Norwegian coast.") However I have taken it in 

 abundance on many occasions throughout the Faroe Channel. It is rather important 

 to establish the identity of Brady's Rh. gigas, and of two preserved specimens at the 

 British Museum, which I have examined, one measured 5 "8 mm. and another 6"0 mm. 

 Both were immature females with four-jointed abdomen, lateral spines on Th. 3 

 (small), and on Th. 4 (large), with none on the fifth segment, resembling Rh. grandis, 

 one dorsal spine on the first abdominal segment (no dorsal spines on the thoracic 

 segments), and so far as could be seen without dissection, the first feet had an 

 exopodite of two segments only, and the fifth pair consisted each of only one ramus 

 of three segments. These two animals were, of course, very much smaller than 

 described by Brady (8*5-10 mm.) and were undoubtedly immature, and the species 

 may well be identical with young Rlt. grandis (Giesbrecht). 



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