DISTRIBUTION AND GENERAL NOTES ON THE SPECIES 381 



and which have to be satisfied with a mainly pelagic diet when in deeper waters. Further, the hake 

 are to be found in the Thysanopsetta area just after they have spawned, and at that time, as is well 

 known, they eat everything within reach. 



The greatest concentrations of Thysanopsetta were found near the southern and inshore limits of 

 its main habitat, in late summer. Its concentration there may be correlated with the relatively warm 

 and intermittently southward flowing inshore surface water. One would suppose it to be a prime 

 requisite for survival that the post larvae should attain the bottom-living stage before being swept 

 north of their ecological norm in the main path of the Falkland current. On these premises it seems 

 a fair hypothesis that spawning will be found to take place near the southern limits of the species' 

 range. It is also possible that the period of the pelagic phase may be shorter than is usual in allied 

 species, thus making for quick settlement upon suitable terrain, but the only factual support for this 

 suggestion comes from a single rich haul of post-larvae secured with the Russell bottom-net, slightly 

 to the south of the main locus of the species, in the late summer of 1930-1 (St. WS832). Here also 

 larvae were taken in plankton nets fished nearer to the surface. Adults have never been taken (in 

 numbers) much farther south than this, so it seems certain that these larvae must have resulted from 

 a very recent spawning: 



Hippoglossina mystacium Ginsburg. Norman (1937, p. 132) records this species (which is closely 

 related to the more northerly H. macrops Steindachner, of the west coast) from Magellan Strait, so 

 it may occasionally penetrate to the eastward, although we did not find any. 



Paralichthys patagonicus Jordan and Goss. This is an east coast species, but its main habitat lies 

 far to the north of the area of the surveys, and we did not capture any. Several specimens of 

 P. microps (Gunther) were obtained by the ' William Scoresby ' off the west coast, but this species is 

 not known to extend 'round the corner'. According to Norman it is sometimes called 'lenguado' in 

 South America, but this common name for flatfish (used for Solea in Spain) is applied so promiscuously 

 that it is safer to regard it as a family name to be applied to any small Heterosomata (just as the ancient 

 word ' butt ' is still used in parts of East Anglia, usually for flounders, but without any intention of 

 specific distinction). 



Paralichthys isosceles Jordan. This is one of two flatfish of the area surveyed that are big enough to 



eat ; it is sometimes over a foot in length and half a pound in weight. We found very small numbers 



not infrequently in shallow water (90 m. and under) in the extreme north. None was taken south of 



lat. 46" S : 



WS762 I WS788B I 



WS762B I WS853 2 



WS763 3 WS852 I (in BTS) 



Xystreurys rasile (Jordan). We found this species also in the extreme north of the area surveyed, but 

 it was very rare. Norman tells us (1937, p. 135) that it, too, is called 'lenguado', which suggests that 



