458 



NOTES AND MEMORANDA. 



Colour-changes in Cottus bubalis. — On May lOtli a specimen of this 

 fish, of a brilliant carmine-red colour, was brought to the Laboratory. 

 It had been caught in a lobster-pot in deep water. The ground 

 colour was a very vivid carmine-red, and this was interrupted at 

 places by black, white, and yellow markings. The black markings 

 were distributed as follows : — There were streaks and bands on the 

 head, a pair of irregular blotchings at the sides of the first dorsal 

 fin, another pair at the sides of the second dorsal, and a pair at the 

 base of the tail, also a pair of black patches on the bases of the 

 pectorals. The white marks were opaque, and had a chalky appear- 

 ance : there was a pair of these in the sides of the body opposite 

 the first dorsal, and a pair of large patches on the sides of the first 

 dorsal fin itself ; there was a similar arrangement of white patches in 

 the region of the second dorsal, and a patch on the middle of each 

 pectoral, also a small white spot on the middle of the dorsal side of 

 the head, and another at the dorsal part of each pectoral. Yellow 

 bands alternated with red along* the rays of the pectoral fins. 



This specimen was placed in one of the table tanks in the Labora- 

 tory ; at the bottom of the tank was coarse yellow gravel, while the 

 sides were of black slate, and there were one or two large dark 

 stones in the tank, behind which the fish usually concealed itself. 

 The tank is very dimly illuminated. 



On June 24th I examined the specimen, and found it was deep 

 black all over the back and sides with the exception of the white 

 markings, which were unaltered ; there was not a trace of red about 

 it. The ventral surface was of course light throughout the experi- 

 ment. 



I then placed the specimen in a pan painted red and strongly 

 illuminated. In a day or two the colour was much lighter, having 

 become a slightly yellowish brown without any red tinge. But the 

 specimen died from accidental stoppage of the circulation in the pan 

 before further observations could be made. 



The ordinary specimens of the shore are black or dark brown on 



