The Origin of the Markings of Caterpillars. 375 



perhaps also be suggested that the oldest Sphingidce 

 lived entirely on low plants among grasses, and in 

 the course of time gradually took to shrubs and 

 trees. At the present time the majority of the 

 Sphinx-larvae still live on low plants, and but few 

 on trees, such caterpillars generally belonging to 

 certain special genera. 



The character of oblique stripes becomes per- 

 fected by the addition of coloured edges, the 

 latter, as is self-evident, having been added subse- 

 sequently. 



The third chief constituent of the Sphinx-mark- 

 ings, i.e. the spots whether perfect ocelli or only 

 ring-spots in two of the special genera here con- 

 sidered, arise on the subdorsal, where they are 

 either deposited (Deilephila), or built up from a 

 fragment of this line (Chcerocampa). That these 

 markings can, however, also originate independ- 

 ently of the subdorsal, is shown by the ocellus of 

 Pterogon CEnotherce, situated on the segment 

 bearing the caudal horn. In this case, however, 

 the ontogeny teaches us that the spot also succeeds 

 the subdorsal, so that we can state generally that 

 all these spot-markings are of later origin than the 

 longitudinal striping. 



two directions of space. If a caterpillar thus marked be placed 

 on a twig, these lines are visible when we look at the creature's 

 back or at either side. That the subdorsal are therefore the 

 primary lines, as shown by Dr. Weismann's observations of the 

 ontogeny of many of the Sphingida^ is quite in harmony with the 

 view of their having been produced by natural selection. R.M.] 



