Coloration of Marine Animals. 223 
present. Thus A. Agassiz notes that the pelagic Globigerine 
floating in masses are occasionally tinted reddish or scarlet, 
and pelagic Infusoria, like Cerat‘um and Peridinium, are of a 
greenish or reddish hue. In such forms the influence of 
Natural Selection or other cause just indicated would appear 
to be slight. 
Tt cannot be said that the bright yellow, white, purple, 
red, and brown hues of littoral sponges, or the blue or pinkish- 
purple of deep-sea sponges, are due to Natural Selection—not 
more, indeed, than the tints of the calcareous corallines. 
Mr. Garstang’s view that they are thus conspicuously coloured 
because they have a nauseous taste is balanced by the fact 
that many are of an extremely sober tint, and that numerous 
palatable animals are equally conspicuous in their hues. 
Moreover, the common crumb-of-bread sponge assumes, under 
the same circumstances, various hues in the tidal region, such 
as brownish, purplish, yellowish, and greenish. ‘The white 
colour of Grantia compressa, Leuconia nivea, and the occa- 
sional purple of Leucosolenia botryotdes are also devoid of 
relation to their surroundings. Further, tufts of Chalina and 
Suberites are occasionally found in the stomach of the cod, 
and sea-lemons browse upon sponges of various hues. The 
opinion of the author just mentioned that the association of 
the red Suberites (which, like other sponges, is, he says, 
intensely disliked by fishes) with Pagurus cuanensts is for the 
benefit of the crab may be true, but Suderites is brownish or 
stone-coloured in some cases, and does not always protect the 
crab from fishes. ‘The view that some crustaceans, a group 
so much sought after by fishes, escape capture by dwelling 
in sponges (Garstang and Poulton) needs confirmation. 
Many annelids and some zoophytes are found in sponges, but 
it has generally been thought that they occur there just as 
they occur under compound ascidians, tangle-roots, and 
Melobesia—viz. for protection. In like manner the crusta- 
ceans and annelids found in the interior of Venus’s fower- 
basket are there for shelter, not because the sponge is 
inedible. 
In considering these views of the coloration of sponges it 
would seem to be as legitimate to state that the forms of 
Chondrocladia virgata and Cladorhiza pennatula (which, for 
the moment, may be supposed to be palatable) were specially 
given them for protection, since they escape search in the 
one case by resembling the backbone of a fish and in the 
other a tiny pinnate zoophyte. 
It is generally stated that the surface-fauna of the ocean is 
transparent or faintly coloured, apparently for the sake of 
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