436 MR. E. W. L. HOLT — STUDIES in [May 1 , 



of the dorsal is free. Besides the specimens in question, I have 

 seen similarly malformed Turbot on several occasions in the 

 Grimsby market, arid have no doubt but that the malformation is 

 common enough. As the authors remark, this condition differs 

 from the Cyclopean only in degree, and I would suggest that the 

 explanation offered above as to the process of development of the 

 Cyclopean malformation is equally applicable to that now under 

 consideration, allowing, of course, for a less degree of want of 

 harmony in the metamorphosis. But, again, quoting Messrs. 

 Cunningham and MacMunn, " it is a very great difference of 

 degree, and does not contradict the conclusions .... formulated 

 as to the correlation of the typical malformation with ambi- 

 coloration." That is true enough, but since the partial malfor- 

 mation is not necessarily accompanied by ambicoloration, it would 

 seem possible to restrict the correlation to the abnormality of 

 the eyes. 



The Brill, as described by the authors, is colourless on the blind 

 side, except for a small patch of pigment just behind the notch of 

 the dorsal, and continuous, through the notch, with the pigment of 

 the ocular side. The inner face of the notch is rounded, there 

 being no abrupt line of demarcation between the ocular and blind 

 sides ; and I am inclined to regard the intrusion of colour as due 

 simply to a migration of chromatophores. Pigment commonly 

 extends on to the blind side of the ventral part of the head in 

 PL micro cephalus, the ventral edge being in this form rounded 

 instead of somewhat abrupt. I have also a young Plaice (PL pla- 

 tessa) which has in some manner been cut through down to the 

 backbone. The wound has healed without the anterior and 

 posterior regions re-uniting, and a certain amount of pigment 

 extends through to the blind side. I think it may therefore be 

 assumed that the Brill is practically normal in the coloration of 

 the blind side. 



The Turbot has a good deal of pigment on the posterior region 

 of the blind side, but others, with a similar hook of the dorsal, I 

 have noticed to be entirely colourless on the blind side, and pigment, 

 as noticed by the authors referred to and others, occurs so commonly, 

 and sometimes to so considerable an extent, on the blind side of 

 otherwise perfectly normal Turbot that there is no reason to 

 suppose that the malformation of the dorsal in this particular 

 specimen has any necessary connection with its partial ambi- 

 coloration. 



The authors mention the frequent occurrence of Turbot and 

 Brill with a row of spots along the interneural and interhamial 

 regions of the blind side, and certainly, in the North Sea, Brill so 

 marked are extremely plentiful. I have not observed it so com- 

 monly in Turbot, the reason being, as I supposed, that such spots 

 are usually marked by a more or less diffuse arraugement of the 

 pigment in ambicolorate Turbot. I do not find any suggestion 

 that these markings of the blind side of the Brill are precisely 

 those which are the most conspicuous in the metamorphosing and 



