136 COLOUR IN NATURE chap. 
been reinvestigated since Moseley’s work. Moseley 
found antedonin also in a deep-sea Holothurian. 
5. Among the Holothuria black or brown pig¬ 
ments are widely distributed, and may be identical 
with those occurring in the Crinoid Holopus and the 
dark-coloured Ophiuroids. In addition, numerous 
bright pigments occur, but are rarely important in 
the production of surface coloration. Among them 
lipochromes are probably common, especially in 
internal organs. In Ocmus brunneus , according to 
M'Munn (1889), the ovaries are pale blue, turning 
red and yielding a lipochrome when treated with 
alcohol and other reagents. This is an interesting 
case, for it seems to be the only one mentioned in 
the literature in which an identity with Crustacean 
pigment can be definitely maintained. 
Relations to Pigments of Crustacea 
Looking at the pigments of Echinoderms as a 
whole, we must remark, first, the prevalence of lipo¬ 
chromes, especially in the star-fishes and brittle-stars 
where they seem to form the predominant pigments. 
Again, the case just mentioned suggests that the blue 
Crustacean pigments—the so-called lipochromogens 
—are found also in Echinoderms, though there is as 
yet no evidence to prove that they give rise to 
external colours. 
So far, there is an analogy with the Crustacea, 
but we find further that the pigment called entero- 
chlorophyll is common in the digestive caeca, in 
the perivisceral fluid and probably elsewhere in 
Echinoderms, while in Crustacea it is, at most, rare. 
