20 DISCOVERY REPORTS 



form or variety, unless connected with the typical form by full series of gradations, as 

 a species. 



For example, the common Lysianassid Orchomenella chilensis occurs in several forms 

 (cf. Schellenberg, 1926) in Antarctic and sub-Antarctic waters. It also occurs in South 

 Africa in a form (f . plicata) so distinct that one may well consider it as a species ; as a 

 species, moreover, which does not occur elsewhere so far as we yet know. But the 

 trinomial system of recording is certainly far better and more accurate than the state- 

 ment that O. chilensis is a variable and widely distributed species. Such a statement 

 would entirely conceal and confuse the facts of geographical distributions. 



A further example of confusion caused by "lumping" is the Nannonyx kidderi 

 "complex", which may be said to have been imposed, and to have imposed, upon all 

 authors since 1909. 



A very great deal of work has yet to be done on the southern fauna before the classi- 

 fication rests on as firm a footing as does that of the northern fauna ; and many points 

 in the latter are still not settled. In the meantime it seems wiser to err on the side of 

 "splitting". 



HISTORICAL 



It may be of interest to give a brief outline of the growth of our knowledge of the 

 Amphipodan fauna of the area primarily investigated by the ' Discovery ', i.e. the South 

 American quadrant ; for this purpose the Chilean and Patagonian coast north of 47 S 

 lat., and also Tristan da Cunha, will be excluded. 



It is rather surprising that the first Amphipod to be described from this region, in 

 fact from the Antarctic, should be a pelagic form and not a littoral form, even though it 

 is the commonest pelagic form there. In 1825 Guerin described Themisto gandichandii ', 

 collected near the Malouines (Falkland Islands) by Gaudichaud, who was botanist on 

 the 'Uranie'. 



Gaudichaud also collected an Anchylomera {abbreviata = blossevillei M. Edw.) and a 

 Phlias (serratus) in the course of a voyage between the Malouines and Port Jackson. 

 These were described by Guerin in 1836. It is probable that both these species were 

 collected in the Southern Pacific. Anchylomera has not been found in the area under 

 discussion; and Phlias has not since been rediscovered, though Stebbing (1899, Trans. 

 Linn. Soc. Loud., p. 417) reported a specimen from the Mediterranean which agreed 

 with the generic characters of Phlias. Both these species, therefore, are here ignored. 



To the enterprise of the early French whalers we owe the important paper by 

 Rousell de Vauzeme on Cyamus in 1834, in which are described the three species of 

 whale louse, ovalis, erraticus, and gracilis, based on specimens collected from "whales 

 harpooned under his own eyes" in the neighbourhood of Tristan da Cunha and the 

 Falklands (see Stebbing, 1888, p. 155). 



In 1848 Milne-Edwards described the huge Amphipod Lysianassa magellanica, col- 

 lected by D'Orbigny from the stomach of a fish caught off Cape Horn. This species has 

 not been rediscovered in the south, though it has been identified with the Arctic 



