^ 



46 A PECULIARLY ABNORMAL SPECIMEN OF THE TURBOT. 



this view may explain the sejparation of the anterior end of the dorsal 

 fin from the head, which occurs in this specimen and in many ambi- 

 colorate specimens. In consequence of the reversion of the head the 

 left side of the body is joined to the right side of the head and vice 

 versa. Thus the dorsal fin, when it grows forwards in the develop- 

 ment, finds itself in abnormal relation to the two sides of the head 

 and therefore fails to unite with the head, but grows out as a free 

 process. The pigmentation of the fish is not precisely in agree- 

 ment with the above hypothesis, since the right side of the head is 

 only incompletely pigmented, and pigment is wanting from the 

 anterior dorsal region of the left side of the body. These deficiencies 

 of pigmentation, whatever their cause, do not appear to me to be 

 sufficient to invalidate my hypothesis, which agrees so well with all 

 the more important peculiarities of the fish. 



EXPLANATION OF PLATE IIL 



Fig. 1. Riglit or upper side of abnormal young Turbot, showing both eyes with 

 some pigment on right side of head, absence of pigment from right side 

 of body. 



Fig 2. Left or lower side of the same sjiecimen, showing absence of eyes and 

 pigment from left side of head, presence of pigment over left side 

 of body. 



