OCT 1 1397 



On a Mode of the Passage of the 

 Eye in a Fiat-Fish. 



By T. Nishikawa. 



Zoological Institute, Imp. Univ., Tokyo. 



On a very quiet and brilliant morning of Aug. 10th. of last year, 

 a transparent young flat-fish was caught with a surface-net at the 

 mouth of the harbor of Misaki. The fish was then swimming vertical- 

 ly ; but when placed in a glass vessel, it turned on its right side and 

 remained motionless on the bottom for hours. It was 1.3 cm. in 

 length and about 0.4 cm. in height. It had no pigment, and was quite 

 transparent. The mouth was asymmetrical, a single nostril was pre- 

 sent on the left side, and the vertical fins were confluent, while the 

 pectorals were not to be seen. The two eyes were then situated symme- 

 trically with reference to the longitudinal axis of the body. Fig. 1 re- 

 presents the profile of the anterior part of this flat-fish, as drawn on the 

 morning of that day. It will be seen that the dorsal lin has already 

 extended itself along the head to the anterior extremity of the snout, but 

 this extended part of the dorsal had as yet no fin rays, only the soft 

 tissues having grown forwards. What is remarkable is that this 



anterior extension, although applied 

 closely to the head, has not coalesced 

 with it, and that at the inner base of 

 the anterior extension, there was a 

 clear large hole passing from one 

 side to the other. The posterior bor- 

 der of the hole was about on a level 

 with that of the eyes. 



As the animal was watched, the 

 right eye gradually travelled, with 



Fig. 1. 



