358 DISCOVERY REPORTS 



southern region, there was in late summer a strong indication of offshore movement, that continued 

 into autumn (c) as one would expect if Genypterus moves offshore in winter like so many other 

 demersal fishes. 



The measurements — too few for detailed consideration — show extremes of size in the north, while 

 individuals caught in the south were more uniform. Possibly the southward movement down the 

 coast and out again is mainly confined to adolescent individuals. Really small young individuals were 

 taken at one northern station only. 



The interesting point that seems fairly certain from the distribution observed is that Genypterus 

 seemed to avoid the central plain of the shelf, being found mainly along the lines of steepest gradient, 

 i.e. the ' first slope ' inshore, and the edge of the shelf to the north. Our only captures of the species 

 on the central plain were near its southern limits in autumn, when those that have worked down the 

 coast are believed to be seeking deeper water. This they seemed to succeed in reaching in the deeper 

 southern portion of the Falkland trough, and since they have not been seen at any of the numerous 

 stations worked in the immediate neighbourhood of the Falkland Islands I conclude that if they 

 further succeed in regaining a more normal, northern habitat, it is by way of the Falkland trough 

 that they do so, as indicated by the dotted portion of the line on the diagram (Fig. 43 d). 



BROTULIDAE 



Cataetyx messieri (Giinther). Two small specimens of this rare fish were taken in deep water beyond 

 the edge of the shelf, one in the intermediate region and one farther south. It has also been recorded 

 from Messier Channel, Chile, and South Africa. A specimen 63 cm. long has been taken in very deep 

 water off Cape Point. E. R. Gunther considered that the normal habitat of the species lies below the 

 depth hmit of ordinary trawling : 



WS248 I WS773 I 



CENTROLOPHIDAE 



Seriolella porosa Guichenot. This species was only captured at a single northern inshore station, 

 WS853 (8), worked early in autumn. The French found it common in Orange Bay, near the eastern 

 end of the Magellan Strait in 1883 (Vaillant, 1888, p. C30), and it might therefore be expected to 

 occur throughout the length of the shelf. Endeavouring to explain our lack of evidence of such 

 extended distribution, E. R. Gunther noted that its shape and colouring suggest fast swimming near 

 the surface, which might help to account for its being missed by the trawl. Alternatively, it may be 

 a strictly coastal species rarely moving offshore so far as the main trawling grounds. 



The species is also known from New Zealand, and from Tasmania, where Neptonemus dobiila 

 Gunther was the synonym used by Johnston (1891), and Seriolella douhla^ Gunther the synonym 

 used by Lord (1923, p. 66). These writers tell us that it is known as 'trevally' or ' mackerel-trevally ' 

 in Tasmania. The closely allied Seriolella brama Gunther, the 'snotgall' or ' snotgall-trevally ' of 

 Tasmania, is also sold under the name of 'trevally' in Christchurch and Dunedin, New Zealand, but 

 in that country the name is more usually (and correctly) applied to Caranx platessa Cuvier and 

 Valenciennes. It is also noteworthy that in Tasmania a true carangid (C. georgianus, Cuvier and 

 Valenciennes) is called ' silver-trevally ' (Lord, 1923, p. 67), while the usual New Zealand name for 

 Seriolella is 'silverfish', which can of course lead to immediate confusion with atherines in that and 

 most other countries, 



1 A misprint. 



