12 DEEP SEA FISHES. 
if it does not make an addition to the supply needed for the support of life. 
In fresh condition the fishes and other animals secured at great depths, 
are tinted with pale greenish to pale yellowish green, or, somewhat rarely, 
to pale bluish. On Plates A to N of the illustrations herewith, the colors 
were taken by Mr. Westergren and Professor Agassiz from the fresh speci- 
men, before it was placed in alcohol. The pale greenish tint is seen to 
affect even such as become intense black when placed in the preserving 
liquids, Plates B and D, and Plate F, figures 1 and 38. That the abyssal 
light is of a pale greenish color is evident from the colors of the animals 
living within it; this proof is not at all confined to the coloration of the 
fishes, it obtains throughout the bathybial fauna. The harmony of colors 
between the creatures of the depths and their surroundings is paralleled 
by that obtaining between the ashy gray inhabitants of the desert and 
the arid wastes in which they live, or between the white in pelage and 
plumage in the Arctic fauna and in its snowy environment. From the 
general coloration of the animals of a particular region the zoologist may 
determine the character of the light by which it has been modified. Deep 
sea investigation has established the fact that life is pretty generally 
distributed on the ocean bed. From this it would appear that similarly 
bathybial light obtains nearly everywhere in the abysses. Probably the 
light of different localities varies in intensity since undoubtedly there are 
sections of the bottom that are more thinly clad with sedimentary deposits 
of organic origin, and consequently lacking in amount and activity of 
chemical interchange, or for other and various reasons not as well adapted 
for the existence of animal life. 
The general greenish tint in the coloration is assimilative and occulta- 
tive, as it renders the bearer like his surroundings and as it hides or con- 
ceals him. It is protective to the prey when it conceals the latter and 
destructive to it when the enemy is rendered invisible. As all the deep 
sea animals are predaceous the tint is helpful to the individual as it hides 
the latter from the enemy or the prey, and harmful as it increases the 
difficulty in discovering and securing the food. The story concerning the 
light at the bottom of the ocean is the same from whatever class of animals 
it is drawn. On the green mud and ooze the light is greenish. 
The lower belt of light, like that at the surface, is inhabited by multitudes 
of species, represented by myriads of individuals. Between the two belts, the 
upper and the lower, there apparently is a belt of darkness, the Azoic belt of 
