Coloration of Marine Animnl'i. 223 



present. Thus A. Agassiz notes that tlie pelagic Globigerina* 

 floating in masses are occasionally tinted reddish or scarlet, 

 and pehigic Infusoria, like Cii\itinni and Periclinium.ixva of a 

 greenish or reddish hue. In such forms the influ<Mice of 

 Natural Selection or other cause just indicated would apjjoar 

 to be slight. 



It cannot be said that the bright yellow, white, purple, 

 red, and brown hues of littoral s|)onges, or the blue or pinkish- 

 purple of deej)-sca sponges, are due to Natural Selection — not 

 more, indeed, than the tints of the calcareous eoridliiies. 

 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 compreasa, Lenconia ni'vea, and the occa- 

 sional purple of Leucosolenia hutnjoides are also devoid of 

 relation to their surroundings. Further, tufts of CfiaUna and 

 Suben'tes arc occasionally found in the stomach of the cod, 

 and sea-lemons browse upon sponges of various hues. Tlie 

 opinion of the author just menlit)ned that the association of 

 the red lSul)ei'it<s (which, like other sponges, is, he says, 

 intensely disliked by fishes) with Pagurus cuancnsis'is for the 

 bent fit of the crab may be true, but Suherites is brownish or 

 stone-coloured in some cases, and does not always protect the 

 crab from fishes. 'I'he view that some crustaceans, a group 

 80 much sought after by fishes, escape ca[)ture by dwelling 

 in sponges (Garstang and Poulton) needs confirmation. 

 Many annelids and some z ophytes are found in sponges, but 

 it has generally been thought that they occur there just as 

 they occur under compound ascidians, tangle-roots, an<l 

 Melohesia — viz. for protection. In like manner the crusta- 

 ceans and annelids found in the interior of Venus's Hower- 

 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 

 (liondrocladia virjata and L'ladnrhiza pennatala (which, f>r 

 the moment, may be sujtposed to be palatable) were specially 

 given them for jirotection, 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 

 transpaiont or faintly coloured, a[)parently for the sake ot 



Ui* 



