Attention is drawn to the fact that cephalopod skin contains reflecting elements (irido-phores, leucophores) in addition to the well-known chromatophores; and the reflexion of monochromatic light from small areas all over the arm, head and body skin in Octopus vulgaris and Sepia officinalis is demonstrated. It is emphasized that the chromatophores of these species contain pigments only at the yellow-red (-black) end of the spectrum so that no combination of their activities could cause the skin to take on the blue or green tinge occasionally seen in the living animal. The function of the chromatophores in cryptic “colouration” is largely limited to tone-matching, colour-matching being dealt with by the reflecting elements. These, when they are revealed by retraction of the overlying chromatophores, automatically reflect incident light of whatever wavelength and thus enable what is probably a colour-blind animal to take on the colour as well as the tone of its surroundings.