242 Studies in the Theory of Descent. 



In this stage also there remains almost always 

 on the three to six front segments, a more or 

 less distinct residue of the subdorsal, which ex- 

 tends backwards from the head as a whitish line 

 intersecting the foremost oblique stripes. (Fig. 

 70, PI. VII.) 



RESULTS OF THE DEVELOPMENTAL HISTORY OF SMERINTHUS 



TlLIJE, POPULI AND OCELLATUS. 



From the meagre materials furnished by these 

 three obviously nearly related species, we may at 

 least conclude that, with respect to marking, three 

 stages of development can be distinguished : 



(1) Simple (green) coloration without marking ; 



(2) subdorsal lines crossed by seven pairs of oblique 

 stripes ; (3) more or less complete absence of the 

 subdorsal lines, the oblique stripes remaining, and 

 showing a tendency to become edged with a 

 red border. 



Which of the three species is the oldest I will 

 not attempt to decide. If we might venture to 

 form any conclusion from the frequency of the 

 red spots, Tilia would be the youngest, /. e., the 

 species which has made the farthest advance. But 

 this does not agree with the fact that the oblique 

 stripes appear somewhat later in this species. 

 Both these distinctions are, however, too unim- 

 portant to enable us to build certain conclusions 

 on them. Neither does a comparison of the adult 



