No. 430.] THE COLORS OF FISHES. 807 
In case of markings on the fins and of elaborate ornamenta- 
tion in general, it is best defined in the oldest and most vigorous 
individuals, becoming intensified by degrees. 
Intensity of Coloration.—In general, coloration is most 
intense and varied in certain families of the tropical shores, 
and especially about coral reefs. But in brilliancy of individual 
markings some fresh-water fishes are scarcely less notable, 
especially the darters (Etheostominz) and sunfishes (Centrar- 
chidz) of the streams of eastern North America. The bright 
hues of these fresh-water fishes are, however, more or less 
concealed in the water by the olivaceous markings and dark 
blotches of the upper parts. 
Coral Reef Fishes. —The brilliantly colored fishes of the 
tropics seem to scorn the need of protective coloration. They 
save themselves from their enemies in most cases by excessive 
alertness and activity (Chatodon, Pomacentrus), or else by 
burying themselves in coral sand (/w/es gaimardi), a habit 
more frequent than has been suspected. 
Fading of Pigments in Spirits.— In the preservation of 
specimens most red and blue pigments fade to whitish, and it 
requires considerable care to interpret the traces which may be 
left of red bands or blue markings. Yet some blue pigments 
are absolutely permanent, and occasionally blood-red pigments 
persist through all conditions. Black pigment seldom changes 
in spirits, and olivaceous markings simply fade a little without 
material alteration. It is an important part of the work of the 
systematic ichthyologist to learn to interpret the traces of the 
faded pigment left on specimens he may have occasion to 
examine. In such cases it is more important to trace the 
markings than to restore the ground color, as the ground color 
is at once more variable with individuals and more constant in 
large groups. In other words, it varies a good deal, but in 
almost constantly narrow limits. 
Variation im Pattern. — Occasionally, however, a species is 
found in which, other characters being constant, both ground 
color and markings are subject to a remarkable range of varia- 
tion. In such cases the actual unity of the species is open to 
serious question. The most remarkable case of such variation 
