The Origin of the Alar kings of Caterpillars. 293 



among caterpillars is shown by the large number 

 of green species. 4 It may be fairly said that all 

 caterpillars which possess no other means of pro- 

 tection or defence are adaptively coloured. These 

 facts are now well known ; so also is the explana- 

 tion of the varied and striking colours of many 

 caterpillars given by Wallace. 6 There is, how- 



4 [Andrew Murray called attention to this fact in 1859 

 ("Edinburgh New Philos. Journ.," Jan., 1860, p. 9). This 

 view is also corroborated by the fact that no internal feeders 

 are green; see note 2, p. 310 and Proc. Zoo. Soc. 1873, P- 

 159. R.M.] 



5 [Proc. Ent. Soc. March 4th, 1867; and "Contributions to 

 the Theory of Natural Selection," ist ed., pp. 117^122; also 

 Darwin's " Descent of Man," 2nd ed., p. 325. Among the 

 most important recent additions to the subject of the colours, 

 spines, and odours of caterpillars, I may call attention to a 

 paper by Fritz MUller (" Kosmos," Dec., 1877), the following 

 abstract of which I communicated to the Entomological 

 Society (Proc. 1878, pp. vi, vii) : "The larvae of Dione Juno 

 and Acraa Thalia live gregariously, and are brown in colour ; 

 they are covered with spines, but, being of dull colours, 

 their spiny protection (which in the case of D, Juno is very 

 imperfect) would not preserve them unless they were dis- 

 tinguished as inedible at the right time, and not after being 

 seized, in accordance with the principles laid down by 

 Mr. Wallace. It is suggested that the social habits of the 

 larvae, which lead them to congregate in large numbers, make 

 up for their want of colour, since their offensive odour then 

 gives timely warning to an approaching enemy. The cater- 

 pillars of Col&nis Julia and Dione Vanilla are equally wanting 

 in bright colours, but are solitary in their habits, and these 

 species rest on the under side of the leaf when feeding. On 

 the other hand, the caterpillars of Heliconius Eucrate^ Colcenis 

 Dido, and C. Isabella, which are of solitary habits, and which 

 freely expose themselves, are very gaudily coloured, and there- 



