No. I.] PECTORAL APPENDAGES OF PRIONOTUS. 1 89 



rays came in contact with it. The fish immediately began to 

 move the free rays much more rapidly than usual, passing them 

 over the piece of meat or fish several times, and then by a 

 rapid lateral movement snapped it up. 



After finding two or three pieces of food the fish were guided 

 by sight, apparently, as they swam across the tank to catch the 

 food before it reached the bottom when fresh pieces were 

 thrown to them. In the large fish ponds of the United States 

 Fish Commission the fish often swam ten feet and were able to 

 secure the food before it reached the bottom, the water being 

 from four to five feet deep. The fish frequently became so 

 excited that any light-colored object was taken into the mouth, 

 such as bones, small pebbles, and pieces of shell. In one case 

 two large specimens of P. evolans rushed at the same piece of 

 meat and missing it caught each other's jaws instead. 



Inedible objects were quickly dropped. Tainted meat was 

 quickly rejected from the mouth although it might be taken in 

 again almost immediately, only to be thrown out. The same 

 piece of tainted meat was sometimes taken by several fish in 

 succession and then lay unnoticed. Pieces of meat dripping 

 with turpentine were swallowed as readily as the pieces which 

 had not been treated with it. 



In order to test the use of the free rays independently of 

 sight the crystalline lenses and cornea were removed from 

 some fish and in other cases the cornea was covered with 

 varnish, balsam, or tar. The repeated experiments were 

 negative in their results, as the fish paid no attention to the 

 food, even when it was placed in contact with the free rays. 



Bateson (13) claims that the Triglidae do not take food at 

 night. I have not been able to prove that Prionotus takes 

 food in darkness. 



To test the effect of removing the free rays, fish were 

 selected which took food readily and the free rays were all 

 amputated close to the body in some cases, and in others they 

 were left of different lengths. 



When the free rays were all removed the fish occasionally 

 detected food by sight. In one case I saw normal movements 

 of the stumps of the free rays when food fell on the bottom of 



