The Origin of the Markings of Caterpillars. 229 



Because in Hippophaes the formation of the 

 secondary ring-spots begins with the red colora- 

 tion of one or two shagreen-dots, it does not follow 

 that the primary spot on the eleventh segment also 

 originated in this manner ; and this is not without 

 importance when we are concerned with the causes 

 which underlie the formation of ring-spots. In 

 Ch&rocampa also, the formation of the primary 

 eye-spots appears to differ from that of the 

 secondary in the latter the black " ground-area" 

 first appearing, and in the former the " mirror- 

 spot." The secondary eye-spots certainly remain 

 rudimentary in this last genus, so that the 

 evidence in support of this conclusion is thus much 

 weakened ; but it must be admitted that we are 

 here on ground still too uncertain to admit of 

 wider conclusions being based thereon. 



As a final result of the investigation, we may 

 advance the opinion that the existing species of 

 the genus Deilephila have reached five different 

 phyletic stages, and that their very different 

 external appearance is explained by their different 

 phyletic ages ; the appearance from these cater- 

 pillars of moths so extremely similar, can other- 

 wise be scarcely understood. 



It may appear almost unnecessary to bring 

 forward additional proofs in support of this inter- 

 pretation of the facts, but in a field where the 

 data are so scanty, no argument which can be 

 drawn from them should be considered as super- 



