348 American Fisheries Society 



may like two or three species, or it may take several different 

 sorts of Crustacea. A few may specially like mollusks and 

 very rarely they may be almost exclusively vegetarians, but 

 certainly to some extent, and in many cases to a very large 

 extent, they select their food. Several different species may 

 prefer the same diet; thus most of the species of Solea espec- 

 ially eat Temora, often with Euterpina and Podon, and 

 Temora is also preferred by the dab (Pleuronectes limanda). 



Some hundreds of the thickback (Solea variegata) were 

 examined, Euterpina and Temora being the usual copepod 

 food, often with Podon. A specimen of 4 mm. can swallow a 

 Temora 1.5 mm. long. Up to at least 11.5 mm. the same kind 

 of food is taken. The dab eats the same sort of food. Over 

 1,000 specimens were examined, Podon being the commonest 

 food, Temora coming next. At 5 mm. copepods were pres- 

 ent. It is thus shown that the dab competes with the soles for 

 food, a fact which may have an important bearing on the small 

 numbers of soles in certain areas. On the other hand the top- 

 knots (Scophthalmus norvegicus) , although occurring with the 

 soles and dabs, hardly ever eat Temora, their favorite food 

 being Pseudocalanus, Metridia coming next, so that although 

 present in numbers they need not be feared as competitors for 

 the food of the sole. At 3.5 mm. a Scophthalmus contains 

 copepods. One of 4.5 mm. contained a Metridia of 2 mm. 

 It must therefore take copepods almost directly it is hatched 

 and it continues eating them until it is well over 12 mm. 



The soles, dab and topknots, as well as the turbot and brill, 

 are all large-mouthed fishes with broad gullets, and these can 

 all take crustacean food almost directly they are hatched, but 

 it is different with the small-mouthed flat fishes, the flounder 

 {Plenronectes flesus), the scaldback (Arnoglossus laterna), 

 and the lemon dab (Plenronectes microcephalus) ; these have 

 very small mouths and narrow gullets and no Crustacea have 

 been found in them until they were much further advanced, 

 not below 8 mm. Most of them are empty in the very young 

 stages and probably eat soft unicellular organisms. This is 



