l he Origin of the Markings of Caterpillars. 303 



case, in which a caterpillar was streaked with brown 

 and green (Fig. 9, PL III.). 



The process of transformation, as already 

 mentioned, advances in such a manner that the 

 intermediate forms diminish relatively to the dark 

 individuals. This is found to be the case with 

 Sphinx Convolvuli, and almost to the same extent 

 with Chcerocampa Elpenor, in both of which species 

 the green caterpillars are the rarest. 10 Forms truly 

 intermediate in colour between green and brown 

 no longer occur, but apparently only different 

 shades of light and dark brown, passing into 

 brownish-black. 



The process has again made a further advance 

 in CJuwocampa Porcellus and Celerio as well as in 

 Pterogon CEnothera. In all these species the 

 green form occurs, 11 but so rarely that very few 

 collectors have seen it. The brown form has 

 therefore in these cases nearly become the 

 predominant type, and the solitary green specimens 

 which occasionally occur, may be regarded as 

 reversions to an older phyletic stage. 



Deilephila Livornica appears to have reached a 

 similar stage, but the caterpillar of this species 

 has been so imperfectly observed, that it is 



10 I am unfortunately not able to give exact numbers show- 

 ing the relative proportions of the different forms, since I have 

 never bred S. Convolvuli from eggs, nor C. Elpenor in sufficient 

 numbers. 



11 [With reference to C. Porcellus, see note 2, p. 188. R.M.] 



