1 88 Studies in the Theory of Descent. 



is stated in the books to occur occasionally in these 

 larvae ; neither have I been able to find any figure 

 of an adult green specimen, so that it must in the 

 meantime be admitted that such specimens, if they 

 occur at all, are exceptional instances. 2 The 

 theoretical bearing of this admission will appear 

 later on. 



RESULTS OF THE DEVELOPMENT OF CHJEROCAMPA ELPENOR 

 AND C. PORCELLUS ; COMPARISON OF THESE WITH THE 

 OTHER KNOWN SPECIES OF CH^EROCAMPA. 



The first stage of Elpenor shows that the most 

 remote ancestor of the genus possessed no kind of 

 marking, but was uniformly green. At a later 

 period, the white longitudinal stripe which I have 

 designated the " subdorsal line " made its appear- 

 ance, and at a still later period this line vanished, 

 with the exception of a few more or less distinct 

 remnants, whilst, at the same time, from certain 



8 [Mr. Herbert Goss states (Proc. Ent. Soc. 1878, p. v.) 

 that according to his experience, the green and brown varieties 

 of C. Porcellus (erroneously printed as Elpenor in the passage 

 referred to) are about equally common, the former colour not 

 being in any way confined to young larvae. Mr. Owen Wilson 

 in his recent work, " The Larvae of British Lepidoptera and 

 their food-plants," figures (PI. VIII., Figs. 3 and 3a) the two 

 forms, both apparently in the adult state. During the years 

 1878-79, my friend, Mr. J. Evershed, jun., took five of these 

 full-grown larvae in Surrey, one of these being the green variety. 

 In order to get more statistics on this subject, I applied this 

 year (1880) to Messrs. Davis of Dartford, who informed me that 

 among 18 20 adult caterpillars of Porcellus in their possession, 

 there was only one green specimen. R.M.] 



