130 
COLOUR IN NATURE 
CHAP. 
similar tints. Some at least of the pigments are also 
similar, but those of the Echinoderms seem to be far 
more numerous. 
i. Star-fishes .— Among these yellow, orange, or 
red colours are exceedingly common. In an account 
of the deep-sea Asteroidea collected by the “ Investi¬ 
gator,” Dr. Alcock gives the colours in the fresh 
condition of 25 forms. Of these 18 were of some 
shade of pink or red, 1 was jet black, 1 gray, 1 
brown, 1 orange, 2 red and yellow combined, 1 
yellow and brown. The lipochrome colours thus 
predominate very largely. Out of the 25, 11 came 
from depths exceeding 1000 fathoms, and all of these 
were of some shade of red or pinkish-orange. There 
is thus some evidence to show that in star-fishes, as 
in Crustacea, the lipochrome colours are conspicuous 
at great depths, while shallow-water forms tend to 
display greater variability of tint. The same state¬ 
ment can also apparently be made of brittle-stars, 
but the star-fishes do not usually extend to the depths 
occupied 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 
of Australia. Another species, L. milaris , also of 
an intense blue colour, is found among coral reefs 
in the Malay Archipelago. It is mentioned by 
Klikenthal as having upon it a parasitic Mollusc— 
Capidus crystallinus —one of the bonnet-limpets, which 
is of exactly the same blue colour. One can only 
regret in these cases that exact chemical observations 
on the spot were impossible. 
