238 AMERICAN FISHES. 
shark in the water below, shining all over with phosphorescence. Now 
this phosphorescence is considered by most naturalists to be due to the 
presence of animalcules, and if so, it may reasonably be presumed that the 
pilot-fishes live on these animalcules, for they are frequently seen clinging 
to the sides of the shark.’’ 
The Pilot-fish does not always leave the vessels on their approach to 
land. In summer, when the temperature of the sea-water is several 
degrees above the average, Pilots will follow ships to the south coast of 
England into the harbor, where they are generally speedily caught. 
Pilot-fish attain a length of twelve inches only. When very young their 
appearance differs so much from the mature fish that they have been 
described as a distinct genus, Wauclerus. This fry is exceedingly common 
in the open ocean, and constantly obtained in the tow-net; therefore the 
Pilot-fish retains its pelagic habits also during the spawning season, and 
some of the spawn found by voyagers floating on the surface is, without 
doubt, derived from this species.* 
The Pilot-fish has been observed in one or two instances about New 
York, and also has been recorded from South Carolina. It is, however, 
rare in the Western Atlantic, and our museums have very few specimens. 
*Giinther : Study of Fishes, p. 414. 
