228 A HISTORY OF FISHES 



one, two, or three years the lower side became nearly as com- 

 pletely pigmented as the upper. 



All Flat-fishes {Heterosomata) are, of course, coloured on one 

 side only, the right side in some species, the left in others. The 

 Arabs have a curious legend to account for this, saying that 

 Moses was once engaged in cooking a Flat-fish, and that when 

 this had been broiled until it was brown on one side the oil 

 gave out; this so annoyed him that he threw the fish into the 

 sea, when, although half cooked, it promptly came to life again, 

 and its descendants have preserved this curious arrangement of 

 colour ever since. Mr. Radcliflfe has described a Russian 

 legend which states that the Virgin Mary heard the tidings of 

 the Resurrection when engaged in eating a Rhombus (Turbot or 

 Brill): "incredulous and as one of little faith she flung the 

 uneaten half of the Rhombus into the water, bidding it, if the 

 message be true, come back to life whole! And lo! this it 

 instantly did!" It sometimes happens that a Flat-fish is 

 captured with pigment on the lower side as well as on the 

 upper. This colouring may take the form of scattered brown 

 or black spots on a white ground, or the hinder part of the lower 

 side may have a complete coloration similar to the upper 

 surface. In the Plaice {Pleuronectes) , for example, the pigmenta- 

 tion of the blind side may even include the red spots so 

 characteristic of this species. Often the pigment extends over 

 the whole body, only the under side of the head remaining 

 white, and in rare cases even this is coloured. This phenomenon 

 of ambicoloration is of particular interest, for it is known that 

 Flat-fishes are descended from symmetrical fishes of the Sea 

 Perch kind, and it has been observed that complete (or nearly 

 complete) pigmentation of the blind side, in whatsoever species 

 it occurs, is almost invariably accompanied by other variations 

 towards this original symmetry. The skin and scales of the 

 lower surface not only assume the colour of those of the upper 

 side, but also resemble them in structure. In a normal Dab 

 (Limanda), for example, the scales on the eyed side are spiny, 

 those on the blind side smooth, but in ambicolorate examples 

 they are spiny on both sides. In the Turbot (Rhombus) bony 

 tubercles are present on the upper surface but not on the lower, 

 but in ambicolorate individuals they are nearly equally de- 

 veloped on both sides. 



Finally, the occurrence of albino fishes, in which no pigment 

 is developed at all, may be mentioned. The body is white, 

 often tinged with pink, but, as a rule, the albinism is not 



