SEA-FISHEKJES LABORATORY. 335 



of the fisherman. The fish, however, is noteworthy in 

 other respects. Fig. 25 is a view from the right side, and 

 indicates the characters in question. The left eye does 

 not occupy the normal position, but is very distinctly on 

 the (secondary) dorsal margin of the head, and, indeed, is 

 easily visible from the " blind " side of the specimen. 

 The right eye occupies the usual position. The anterior 

 extremity of the dorsal fin is the most interesting 

 character exhibited by the specimen. It was first 

 suggested by Traquair that the forward extension of the 

 dorsal fin in the median, or pseudomesial, dorsal line, 

 irrespective of the asymmetry of the head, took place after 

 this asymmetry, due to the translocation of the eye, was 

 completed; and that the fin, though apparently arising 

 from the head region, does not really belong to that 

 region at all. In the specimen before us this hypothesis 

 is verified, so far as the facts go. The eye not having 

 crossed the pseudomesial line of the head, it is obvious 

 that the forward extension of the dorsal fin to its normal 

 position, with the anterior extremity just over the middle 

 of the eye, cannot take place. But we find that, though 

 the arrested shifting of the eye has prevented this forward 

 extension of the fin, the latter has still grown, and now 

 arches over the eye so that its anterior extremity is nearly 

 in the position it would have occupied had the eye 

 attained its definitive position. 



