v COLOUR-PHENOMENA IN WORMS ioi 
to form in alcohol a pure green solution without 
fluorescence, and so to offer a marked contrast to 
bonellin. It seems most probable that this pigment 
is related to some of the derivatives of bonellin. 
The same pigment appears to occur in smaller 
amount in some other species of Thalasseina and 
in Hamingici. Both these genera are further stated 
by Lankester to contain haemoglobin in the peri¬ 
visceral fluid and muscles. 
In the Sipunculoidea, another order of Gephyreans, 
integumental pigments appear to be absent, but in 
Sipunculus and Phascolosonia the oxidised blood 
contains a deep red pigment called by Krukenberg 
haemerythrin. This resembles haemocyanin in being 
colourless when reduced, and probably in having 
a respiratory function. It belongs to a group of 
pigments called by Krukenberg the Floridines, 
characterised by their solubility in water and 
glycerine, and their insolubility in the usual organic 
solvents, such as alcohol, ether, chloroform, etc., as 
well as by the readiness with which they undergo 
oxidation. This pigment is similar to the one 
already mentioned as occurring in the sponge 
Hircinia; it is, however, difficult to believe that it 
can be respiratory there. 
The Colours of the Ch^etopoda 
The colours of the Chsetopoda often display great 
beauty, and may be structural or pigmental, or due to 
a combination of the two. One of the simplest forms 
of structural colour is that displayed by the earth¬ 
worm, where the cuticle exhibits a faint iridescence 
