174 ANIMAL COLORATION. 



other animals besides lepidoptera — to many invertebrates^, 

 for instance. 



Warning Colours of Nudibranchs. 



Some interesting experiments have been carried out by 

 Prof. Herdman and one of his pupils* upon the palatability 

 of nudibranchs ; these animals form a group of the Moilusca, 

 and are usually marked by a very varied and brilliant colora- 

 tion. Sometimes this coloration is such as to conceal the 

 molluscs when feeding amid their usual surroundings ; in 

 other species the colours are so disposed as to render them 

 conspicuous anywhere. Experiments were tried with both 

 kinds of nudibranchs — i.e., those that resemble their usual 

 environment, and are therefore, as it is termed, " protectively 

 coloured," and those that exhibit " warning colours." 



Doris lamellata, an instance of the first kind, was eaten by 

 no fish, but " seized and rejected " by a number. 



Ancula cristata, a species conspicuously ornamented with 

 bright yeUow, was " seized and rejected " by thirty-eight 

 fish, "touched and rejected" by a few, and eaten by three 

 individuals. 



Dendronotus arborescens, a protectively-coloured species, was 

 eaten by some fish and rejected by others. 



Eolis, another nudibranch exhibiting warning colours, was 

 taken into the mouth but never eaten. 



These experiments certainly prove that the nudibranchs 

 used are, on the whole, distasteful to the fishes which were 

 attempted to be fed with them ; this even applies to the 

 protectively-coloured forms. Mr. Bateson has moreover shown 

 that certain fishes do not seek their food by sight at all, and 

 therefore no amount of colour protection or warning would 



* Trans. Biol. Soc, Liverpool, vol. iv., p. 131, etc. 



