166 THE COLOUES OF ANIMALS 



"Warning Colours are probably wide-spread among 

 marine organisms. Mr. Garstang had suspected that 

 the bright colours of certain compound Ascidians were 

 of warning significance, because these helpless animals 

 are thus rendered extremely conspicuous, and because 

 some of them emit a most unpleasant odour. He now 

 finds that fish invariably refuse them : although some- 

 times tasted or even swallowed, they are never retained. 

 The bright colours of many sea-antmones and sponges 

 are probably to be explained in the same way. Evi- 

 dence in favour of this conclusion is given on pp. 



200-204. 



( 



Warning Colours in Caterpillars : the history of their 

 discovery 



Warning Colours are greatly developed in insects, 

 and an account of the first recognition of this prin- 

 ciple among caterpillars is of great historical interest. 

 When Darwin was investigating the bright colours of 

 animals, and was elaborating his theory of their ex- 

 planation as of use in courtship, he came across the 

 brilliant colours of certain caterpillars, and saw at 



tensely poisonous spines on its gill-covers, and is rendered conspicuous 

 by a deep black first dorsal fin. The body of the fish is completely 

 buried in the sand, which it resembles in colour, the black fin alone 

 being seen. Mr. Garstang thinks that this conspicuous character 

 prevents such fish as gurnards from mistaking the weever for the 

 dragonet (Callionymus lyra), which is similar in size and habits. He 

 has frequently found the dragonet in the stomachs of gurnards, but 

 the weever never. 



