The colour of the deep-sea Cœlenterates has unfortunately not been recorded in all cases, but still the few observations that we have show that in this group, as in the last, almost every tint and shade are represented. The colouring of the deep-sea jelly-fishes is said to be usually deep violet or yellowish red. However ‘a species of _Stomobrachium_,’ says Agassiz, ‘is remarkable for its light carmine colour, a tint hitherto not observed among Acalephs.’ Moseley records most minutely the colour of some of the deep-sea anemones and corals, and calls attention to the very general presence of madder brown in the soft parts. Agassiz says: ‘Among deep-sea Actiniæ, a species of a new _Cereanthus_ was of a dark brick-red, while other actinians allied to _Bunodes_ were of a deep violet. Actinauge-like forms with tentacles of a pinkish-violet tinge frequently have the column of a yellow shade. The Zoanthidæ were greyish-green.’ And again, in his narrative of the voyage of the ‘Blake,’ he records that ‘some of the deep-sea corals are scarlet, deep flesh-coloured, pinkish orange, and of other colours,’ and in referring to the Gorgonian _Iridogorgia_ he says: ‘The species are remarkable for their elegance of form and for the brilliant lustre and iridescent colours of the axis, in some of a bright emerald green, in others like burnished gold or mother-of-pearl.’ The fauna of the deep sea then, taken as a whole, is not characterised by the predominance of any one colour. The shades of red occur rather more frequently than they do in the fauna of any other zone or region, but whether this is in any way connected with the fact that red is the complementary colour to that of the phosphorescent light, in which many of these animals live, it is at present difficult to say; it is possible that, when we have further information concerning the colours of the animals living in the deeper parts of the Neritic zone, another explanation may be forthcoming. Moseley points out that there are no blue animals known to live in deep water, and it might be added that green is extremely rare as a colouring matter in abysmal animals, although the phosphorescent light given out by some of the echinoderms is green. Blue, as a colouring matter of marine animals, living on the surface or in shallow water, is not uncommonly met with, distributed in the form of bands or stripes, but green is extremely common in fishes, crustacea and cœlenterates, and it is a point of very considerable importance that in this respect there is a very great difference between the deep-sea and the shallow-sea faunas. If a considerable collection of living abysmal forms could be placed upon one table and a similar collection of shallow-water forms upon another, I believe that the first general impression upon the mind of one who saw them both for the first time would be the presence of green colours in the last-named collection, and the absence of it in the other.