GENERAL FACTS ABOUT SEA FISH 35 



able time at the surface, the explanation being simply that their 

 swimming and possibly also their breathing apparatus do not 

 qualify them for such an effort. A further confusion, however, 

 arises in any scheme for differentiating between the surface 

 and the ground fishes. Not alone do the former, as mentioned, 

 habitually go to the bottom, either at fixed seasons or under 

 stress of temperature or weather, but the young forms, larval 

 and post-larval, of many ground-dwelling fishes are strictly 

 pelagic, passing all their early days in the surface water. 



The great abundance and variety of fishes in British seas 

 have already been noticed in connection with the migrations of 

 northern and southern forms, and Forbes long ago remarked 

 on their convenience as a kind of half-way house for these 

 wanderers. Palacky points out that a few typically northern 

 forms are either very rare — as Sebastes, Cottus quadricornis, 

 Gobius nilssoni^ and Lumpenus lampetriformis — or altogether 

 wanting, as Cottus liljeborgi, Onos* reinhardti, and Stomias 

 ferox.'\ On the other hand, by way of compensation, he 

 remarks on the southern forms that find their way to our 

 seas, such as Holocanthus tricolor^ Peristethus cataphractus, 

 Dentex, "Box, Luvarus imperialis, Lichia glauca, Centriscus 

 scolopax, Fierasfer dentatus, Balistes capriscus, Mur^ena helena^ 

 Pristiurus melanostoma, Pagellus bogaraveo, and others. More 

 on the subject of these rare British fishes will be found in a 

 chapter (XIV.) which it has been thought desirable to devote 

 to them, rather than to introduce them in the order that should 

 strictly be theirs, distributed over the other chapters on the 

 different families. 



The study of animal distribution always presents itself in 

 one of two aspects. Either we may investigate the geographical 

 range of a given form, or we may determine the number and 

 variety of forms that inhabit a given area, seeking their affinities 



* I.e. Motdla (rocklings). 



t All of these, together with Gadus esmarkii, have since been taken by 

 Murray on the west coast of Scotland. 



