From a Drawing by Miss Annie Willis. 
Big. 1. LOWER SIDE OF A PIEBALD PLAICE. 
Showing the pigment developed after six months’ exposure to light. 
A PIEBALD PLAICE. 
By J. I. CUNNINGHAM, M.A., F.Z.S. 
lee is well known that the plaice and other fishes of the family of Flat-Fishes or 
- Pleuronectidee arc normally coloured on the upper side and white on the Jower. 
The whiteness of the lower side is due to the absence of black and coloured pigrients 
and the presence of a white substance in the skin. For convenience in description we 
may restrict the term “pigment” to the colouring-matters, excluding the white substance. 
Specimens of plaice and other flat-fishes are, however, occasionally obtaimed which 
show more or less colour on the lower side, varying from small patches to complete 
pigmentation of the whole surface. Conversely, specimens also occur in which pigment 
is entirely absent from part or all of the upper side, the lower side being white as 
usual. The colourless area in such specimens is usually sharply defined, and there is 
no gradual transition from the coloured region to the uncoloured. The lower figure of 
the coloured plate represents a living piebald plaice which came into my possession at 
the Plymouth Laboratory a few years ago. It was caught by a seime-net in the 
Hamoaze, the estuary of the mver Tamar, and was kept alive in the aquarium. 
The occurrence of such specimens seems at first to disprove completely the hypothesis 
that the absence of colour from the lower side in ordinary flat-fishes is due to,the fact 
that no light falls upon that side. At the Plymouth Laboratory 1 carried on for some 
years experiments to ascertain whether pigment would be developed on the lower sides 
of flounders when those sides were exposed to the light. For this purpose the fish were 
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