30 COLOUR IN NATURE chap. 



imilar tints. Some at least of the pigments are also 

 imilar, but those of the Echinoderms seem to be far ^ 

 nore numerous. 



I. Star -fishes. — 'Among these yellow, orange, or 

 ed colours are exceedingly common. In an account 

 if the deep'Sea Asteroidea collected by the " Investi- 

 gator," Dr. Alcock gives the colours in the fresh 

 ondition of 25 forms. Of these 18 were of some 

 hade of pink or red, i was jet black, i gray, i 

 )rown, I orange, 2 red and yellow combined, i 

 ■■ellow and brown. The lipochrome colours thus 

 )redominate very largely. Out of the 25, 11 came 

 rom depths exceeding 1 000 fathoms, and all of these 

 rere of some shade of red or pinkish-orange. There 

 s thus some evidence to show that in star-fishes, as 

 n Crustacea, the lipochrome colours are conspicuous 

 .t great depths, while shallow-water forms tend to 

 lisplay greater variability of tint. The same state- 

 nent can also apparently be made of brittle-stars, 

 )ut the star-fishes do not usually extend to the depths 

 )ccupied by the former. 



Among shallow-water star-fishes we may mention 

 Linckia Icevigata, in which the upper surface is a bright 

 Antwerp blue, the tube feet being chrome yellow. 

 This species inhabits the waters of the Barrier Reef 

 Df Australia. Another species, L. milaris, also of 

 in intense blue colour, is found among coral reefs 

 n the Malay Archipelago. It is mentioned by 

 Kiikenthal as having upon it a parasitic Mollusc — 

 Capulus crystallinus — one of the bonnet-limpets, which 

 !s of exactly the same blue colour. One can only 

 regret in these cases that exact chemical observations 

 3n the spot were impossible. 



