The Origin of the Markings of Caterpillars. 1 79 



by fine transverse rings, as was also the case in the 

 first stage. 



At the beginning of the present stage no trace 

 of the eye-spots could be detected ; but a few days 

 after the first moult it was observed that the white 

 subdorsal line was no longer straight on the fourth 

 and fifth segments, but had become curved upwards 

 into two small crescents. The latter soon stood 

 out more strongly, owing to the filling up of their 

 concavities with darker green. These are the 

 first rudiments of the eye-spots (Figs. 19 and 30). 

 A very fine white line now connected the spiracles 

 (infra-spiracular line), and could be traced from 

 the last segment to the head. This line takes 

 no further part in the subsequent development of 

 the markings, but disappears in the following 

 stage. The blood-red colour of the base of the 

 black caudal horn is retained till the fifth stage, 

 and then also disappears. 



Before the second moult, which occurs after 

 another period of 5 6 days, the caterpillars, which 

 were about 1.3 centimeters in length, had assumed 

 their characteristic tapering, slug-like form. I did 

 not notice that the larvae at this stage possessed 

 the power of withdrawing the three foremost 

 segments into the two succeeding ones, as is so 

 frequently to be observed in the adults ; neither 

 were these two segments so strjkingly enlarged as 

 they are at an earlier period. 



N 2 



