146 ANNALS OF SCOTTISH NATURAL HISTORY 



1908. lUit I am holding this and later correspondence 

 over during the course of further inquiry, and because this 

 paper has already reached so great a length to date of 

 going to press. 



AN AMBICOLORED TURBOT WITH EYES 

 APPROXIMATELY NORMAL IN POSITION. 



By James Ritchie, M.A., B.Sc. 



At an early stage in their life-history Flat-fishes give up 

 the symmetrical mode of swimming possessed by their larval 

 forms and, toppling to one side or the other, adopt the 

 peculiar habit which characterises the adult. Normally in 

 the horizontally swimming adults the upper surface is 

 pigmented and bears both eyes, v/hile the under surface is 

 both colourless and eyeless. But occasionally specimens 

 are found of which both sides are coloured ; and where the 

 pigmentation of the under surface is complete it is generally 

 associated with deformities in the dorsal fin and in the 

 position of the eyes. So well known, indeed, is this associa- 

 tion between complete pigmentation and eye-abnormality 

 that Couch, referring to the Common Flounder, says that 

 such a variation has " occurred so frequently in some districts 

 as to have raised the suspicion of its being truly a distinct 

 species." ^ 



In the Turbot, however, examples of complete two- 

 sided pigmentation are rather unusual, although a partially 

 coloured under surface is by no means so rare. The present 

 example, kindly sent me for examination by Mr. Tom Cook, 

 fishmonger, Edinburgh, was caught, in May of the present 

 year, off the Berwick Bank at a depth of some twenty 

 fathoms. It is a moderately-sized male Turbot {Rhombus 

 maximus)^ 492 mm. in length from tip to tip, and 306 mm. 

 in greatest breadth (excluding the fins). The body propor- 

 tions and the number of fin-rays are normal, but both sides 

 are completely pigmented. The upper surface is of a very 

 dark olive-brown with slightly paler, irregular patches half- 



1 Couch, J., " Fishes of the British Islands," vol. iii. p. 198. 



