38 MR A. O. WALKER ON AMPHIPODA 



Ampliipoda of tlie ' Southern Cross ' Antarctic Expedition. 

 By Alfred O. Walker, E.L.S. 



[Eead IStli December, 1902.] 



(Plates 7-11.) 



The Anipbipoda which form the subject of this paper were 

 collected during the Expedition of the ' Southern Cross,' 

 commanded by Capt. Borchgrevink, to the Antarctic Seas from 

 April 5, 1889, at Cape Adare, to Eeb. 18, 1900, at Eranklin 

 Island. By far the larger part of the collection was made affer 

 the lamented death of Mr. N. Hanson, the Zoologist of the 

 Expedition, by Mr. Anton Eougner, partly by dredging at depths 

 varying from 10 to 26 fath. and partly on the beach at Cape Adare. 

 It is impossible not to be struck with the general resemblance 

 of the collection, both as regards the number and size of 

 individuals and the great preponderance of the Ljsianassidae, 

 to such a collection as might be found in the Arctic Seas ; 

 and with the equally great difference in these respects from any 

 collection that might be made under similar conditions of depth, 

 &c., on our own or on tropical coasts. Although I have only 

 ventured to refer one species to a known Arctic form {Ampelisca 

 onacrocepJiala, Lilljeborg, found also on our own coasts), yet I 

 have only had occasion to make a single new genus (Oradarea). 

 And several of the new species are only separated from Arctic 

 forms by very slight differences — indeed the genera of the 

 Lysianassidse have been separated by Gr. O. Sars on such fine 

 distinctions that the species are reduced to almost infinitesimal 

 differences. Thus OrcTiomenella pinguides is very near to 

 O. pinguis, Boeck ; O. Franklinii to 0. minuta (Kroyer) ; 

 Oediceros Neionesii to O. saginatiis, Kroyer, &c. One of the 

 most interesting forms is Atglus antarcticus, which differs only 

 in very unimportant details from A. carinatus (Fabr.), a species 

 that according to Gr. 0. Sars has only once been taken south of 

 the Arctic Circle, and then in the stomach of a fish ! Yet, with 

 perhaps the exception of Halirages Huxleyanus (Bate), which 

 Sars thinks ought to be referred to Atylus * (notwithstanding a 

 quite different telsou), no other species of the genus as restricted 

 by Sars has been found as yet in the enormous intervening area. 



* Crustacea of Norway, voL i. p. 471 ; cf. p. 436. 



