306 Studies in the Theory of Descent. 



Peltiger, according to Mr. Reading's description (Newman's 

 " British Moths," p. 438), is another case in point. In 

 1874 a number of instances were published by Mr. Thomas 

 G. Gentry in a paper entitled " Remarkable Variations in 

 Coloration, Ornamentation, &c., of certain Crepuscular and 

 Nocturnal Lepidopterous Larvae " (" Canadian Entomologist," 

 vol. vi., p. 85. See also W. H. Edwards' description of the 

 summer and autumnal larvae of Lyc&na Pseudargiolus ; Ibid. y 

 vol. x., pp. 12, 13). 



The caterpillars of the Sphingidce appear also in some cases 

 to vary in a manner very suggestive of phytophagic influences. 

 The observations upon S. Ocellatus recorded in the previous 

 note (p. 241) may perhaps be interpreted in this sense. In 

 order to get experimental evidence upon this subject, I may 

 add that Mr. E. Boscher was good enough at my request to 

 repeat his observations, and conduct some breeding experiments 

 during the present year (1880). In the same locality as that 

 previously mentioned, seven larvae were found feeding on Salix 

 viminalisy all of which were the bright green spotted variety ; 

 and in the same osier-bed six more were found on another 

 species of Satz'x, two of these being the bluish-green variety, 

 and the other four the bright green form. Unless we have 

 here a local race, these observations, in connection with those of 

 last year, tend to show that the light green form is associated 

 with Salix viminalis. When found in the natural state feeding 

 on apple, the caterpillar of this species is generally, perhaps 

 invariably, the bluish-green form. In order to try the effect of 

 breeding the larvae ab ovo on distinct food-plants, a large number 

 of eggs laid by a female Ocellatus in July were divided into 

 three batches, one being supplied with Salix triandra, another 

 with S. viminalis, and the third lot with apple. The experi- 

 ment unfortunately failed in great part, owing to most of the 

 larvae dying off, three from .. the third lot only surviving ; but 

 these were all of the bluish-green form, which colour was 

 shown by all the caterpillars of this batch from their earliest 

 stage. The observation is thus so far successful, as it goes 

 to support the view that the variety mentioned is associated 

 with apple (and S. triandra .?) My friend Mr. W. J. Argent 

 informs me that he had a number of specimens of Sphinx 



