294 Studies in the Theory of Descent. 



ever, novelty in the proof contained in the fore- 

 going descriptions of larval development, as to 



fore most conspicuous. As examples of nearly allied larvae, 

 of which some species are gregarious and others solitary, Fritz 

 Miiller mentions Morpho and Brassolis^ which are gregarious ; 

 while Opsiphanes and Caligo are solitary. The larva of Papilio 

 Pompeius also is gregarious, and those of P. Nephalion, P. 



Polydamas, and P. Thoas are solitary Fritz Miiller 



sums up his observations by remarking that those caterpillars 

 which live alone, and lack the bright colouring as a sign of 

 offensiveness, must hide themselves ; as those of C. Julia and 

 D. Vanilla. The spiny covering is much less a protection 

 against birds than against smaller enemies ; and they may, by 

 the protective habit of living together, diffuse around themselves 

 an offensive atmosphere, even to man, and thus gradually be- 

 coming shorter (as with D. Juno], the spines of these cater- 

 pillars become useless, and finally are altogether dropped." 

 See also Sir John Lubbock's " Note on the Colours of British 

 Caterpillars," Trans. Ent. Soc. 1878, p. 239. Mr. Peter 

 Cameron finds (Trans. Ent. Soc. 1880, pp. 71 and 75) that 

 these remarks are also applicable to the larvae of certain saw- 

 flies. In 1877 Mr. J. W. Slater published a paper "On the 

 Food of gaily- coloured Caterpillars" (Trans. Ent. Soc. 1877, 

 p. 205), in which he suggested that such caterpillars might 

 derive their distasteful qualities from feeding on plants con- 

 taining poisonous or otherwise noxious principles. A much 

 larger number of observations will be required, however, 

 before this view can be accepted as of general application. 

 A beautiful illustration of the theory of warning colours is 

 given by Belt in his "Naturalist in Nicaragua," p. 321. All 

 the frogs found in the woods round St. Domingo are, with one 

 exception, protectively coloured ; they are of nocturnal habits, 

 and are devoured by snakes and birds. The exception was a 

 species of bright red and blue colours, which hopped about 

 by day and made no attempt at concealment. From these 

 facts Mr. Belt concluded that this species was inedible, and on 

 trying the experiment with ducks and fowls this was found to 

 be the case. R.M.] 



