The Origin of the Markings of Caterpillars. 309 



The biological significance of marking if such 

 significance it possess will be most easily inves- 

 tigated by examining whether species with similar 

 markings have any conditions of life in common 

 which would permit of any possible inference as 

 to the significance of the markings. 



Among the Sphingidcz we find four chief forms 

 of marking ; (i) complete absence of all marking ; 



(2) longitudinal stripes ; either a simple subdorsal 

 or this together with a spiracular and dorsal line ; 



(3) oblique stripes; (4) eye-spots and ring-spots, 

 single, paired, or in complete rows. 



Now if we consider in which species these four 

 kinds of marking are of general occurrence, not 



together with their larvae (in alcohol) and cocoons (Proc. Ent. 

 Soc. 1879, p. xvi),and in an accompanying note he stated that 

 the male larva when living is ,of " a bright emerald green, with 

 red and pink markings on the back, and yellow, black, and 

 white streaks on the sides." The male larva is described as 

 being smaller than the female, and as possessing all the 

 brilliant colours, the latter "having no red markings, but only 

 white, yellow, and green, with a little black." I was at first 

 disposed to think that we might be dealing here with two dis- 

 tinct species having differently marked larvae ; but Mr. Francis 

 this present year (1880) forwarded a large number of the living 

 cocoons of this species, which I separated according to size, 

 and, on the emergence of the moths (August), I found that all 

 those from the small cocoons were males, and those from the 

 larger cocoons females. There can be no doubt, therefore, 

 that we have but one species in this case, the larva of which 

 presents the remarkable phenomenon of sexual difference of 

 coloration. As an analogous fact I may here mention the 

 well-known case of Orgyia Antiqua^ the larva of which differs 

 in the colour of the tufts of hair according to sex. R.M.] 



