CHAPTER VI 



THE COLOURS OF CRUSTACEA AND ECHINODERMA 



Nature of Colours of Crustacea — Colour-variation — Pigments 

 of Crustacea : (i) Lipochromes, (2) Soluble Blues — Re- 

 lations of Two — General Characters of Pigments — The 

 Colours of Echinoderma : (i) Star-fishes, (2) Brittle-stars, 

 (3) Sea-urchins, (4) Crinoids, (5) Holothurians — Pigments 

 of Five Classes — Relations to those of Crustacea. 



We shall in this chapter discuss both the Echino- 

 derma and the Crustacea — not that there is any 

 morphological affinity between them, but because 

 there is considerable resemblance as regards pigments. 

 In both, moreover, there is a tendency for lime salts 

 to be associated with the coloured regions. 



Nature of Colours of Crustacea 



The coloration of the Crustacea presents many 

 points of very great interest ; the beauty of the 

 colours, their adaptation to the surroundings, and 

 their great variety combine to render the subject 

 peculiarly attractive. 



It is unnecessary to dwell upon the general 



