The Origin of the Markings of Caterpillars. 347 



and enhance the efficacy of the protective colour- 

 ing. 



5 . Subordinate Markings. I f, from the foregoing 

 considerations, it appears that the three chief ele- 

 ments of the Sphinx-markings longitudinal and 

 oblique stripes, and spot formations are not purely 

 morphological characters, but have a very decided 

 significance with respect to their possessors, there 

 should be no difficulty in referring the whole of 

 the markings of the Sphingidce to the action of 

 natural selection, supposing that these three kinds 

 of marking were the only ones which actually 

 occurred. 



In various species, however, there appear other 

 patterns, which I have comprised under the term 

 "subordinate markings," some of which I will 

 select, for the purpose of showing the reasons which 

 permit of their being thus designated. 



I ascribe to this category, for example, that fine 

 network of dark longitudinal streaks which often 

 extends over the whole upper side of the cater- 

 pillar, and which is termed the "reticulation.'' 

 This character is found chiefly in the adult larvae 

 of Chczrocampa, being most strongly pronounced 

 in the brown varieties : it occurs also in Deilephila 

 Vespertilio, Pterogon (Enothera, and Sphinx Con- 

 volvuli. As far as I know, it is only associated 

 with adaptive colours, and indeed occurs only in 

 those caterpillars which rest periodically at the 



