THE COLORATION OF REEF FISHES 579 



in their environment. It dominates the coloration of such types 

 as Atherina, Stolephorus, Tylosurus and Hemirhamphus, which 

 typically occur at high levels. Among representatives of this 

 group at Tortugas the simple green color is distinctly interrupted 

 only by a silvery lateral stripe, which seems to occur nowhere 

 except upon fishes of this habit, and suggests that pattern, no 

 less than color, may not be wholly fortuitious. 



The correlation of green with its presence in the normal habitat 

 of the animals displaying it is best shown by study of those 

 seined upon reef flats covered by turtle grass. These are not of 

 clear and uniform green color. The plant's flat, narrow leaves 

 may be too short, and the vertical branches of the rootstock from 

 which they spring too far apart for the sand to be completely 

 concealed. In each tuft the older, outer leaves, whose death 

 and detachment approach, are brown. While they retain their 

 connection, or lie scattered among the others, their contribution 

 to the color complex is important. 



In this composite environment of which greenness is, never- 

 theless, the distinctive quality, fishes have been taken as shown 

 in the following table. 



The table includes twenty-four species. Eleven of these are 

 wholly or largely of an unchangeable green color, or have defi- 

 nite green phases, which are assumed in the midst of green sur- 

 roundings. That this should be true of so large a proportion 

 of the total catch among the grass, is perhaps more than might 

 have been anticipated. It certainly demonstrates that green, 

 like the other colors, is distributed according to system, for with 

 the exception of one group there is probably no other in which 

 it occurs with such frequency. Yet the statement above is 

 mechanical and expresses the truth imperfectly; the facts cer- 

 tainly merit more careful analysis. 



These twenty-four species are not members of one bionomic 

 association. Some of them may be excluded from consideration 

 after brief review of the evidence. 



Synodus and the flounder may both be seined on sandy bottoms 

 adjacent to the grass flats. Both are accustomed to bury them- 

 selves more or less completely when resting. Both are marked 



THE JOURNAL OF EXPEBIMENTAL ZOOLOGY, VOL. 23, NO. 3 



