1897.] Nocturnal Protective Coloration of Mammals, Ete. 103 
squids, usually taken on their nocturnal colors, though these 
generally soon fade out. 
A species of file-fish (Monacanthus) which has, in the day 
time, mottled olive-green and brown colors, with slightly darker 
fins and tail, when sleeping becomes pallid gray, or’nearly 
white, and the fins and tail become black. This and other 
related species took curious positions while asleep, often lean- 
ing up obliquely, with the back against the glass of the aquaria 
and the abdomen resting on the bottom ; sometimes, also, lean- 
ing up in a corner of the aquarium with the body curved, or 
against stones in similar attitudes. 
The tautog or black fish (Tautoga onitis) usually sleeps on 
one side, resting under the edges of rocks, or half buried in 
sand or gravel, much after the manner of flounders. They 
` often had their bodies variously bent. This fish did not show 
any marked change of colors, but its ordinary dark colors are 
nocturnally protective. 
The common squid, when resting quietly on the bottom, late 
at night, and apparently asleep, takes on its darkest colors, due 
to the full expansion of the brown and purple chromatophores, 
so that the color is much like that developed when excited 
in the day time, and similar to the usual color of alcoholic 
Specimens. When swimming quietly in the day time the usual 
color is pallid or translucent bluish-white, with very small, 
Scattered, dark specks, due to the strongly contracted chroma- 
tophores. It takes this color, also, when resting upon the light 
sandy bottoms, waiting for the approach of the small fishes on 
which it feeds. It has the power of changing its colors at will, 
but its nocturnal color is probably automatic and protective. 
