The Origin of the Markings of Caterpillars. 209 



appears to me to be of but very little importance, 

 as I shall now proceed to show from the develop- 

 ment of D. Vesper tilio. 



DEILEPHILA VESPERTILIO, FABRICIUS. 



Hitherto I have unfortunately been unable to 

 obtain fertile eggs of this species, so that I can 

 say nothing about the first stage. The latter 

 would have been of interest, not only because of 

 the marking, but also because of the presence of a 

 residual caudal horn. 



I am likewise only acquainted with the end of 

 the second stage, having found, at the end of June 

 1873, a single caterpillar on Epilobium Rosmarini- 

 folium } }\!&\. previous to its second ecdysis. In the 

 case of such young caterpillars, however, the new 

 characters which appear in the succeeding stage 

 are generally perceptible through the transparent 

 chitinous skin at the end of the preceding stage, 

 so that the markings of the insect are thus caused 

 to change. The caterpillar found was about 16 

 millimeters long, and of a beautiful smooth and 

 shining grass-green (Fig. 13). A broad white 

 subdorsal line extended from the first to the penul- 

 timate segment, from which the horn was com- 

 pletely absent. On close inspection the first traces 

 of the ring-spots could be detected near the anterior 

 edge of each segment as feeble, round, yellow, 

 ill-defined spots, situated on the subdorsal line it- 

 self (Fig. 13). On the first segment only there is 



