220 St^t,dies in the Theory of Descent. 



The spots on the subdorsal line decrease from the 

 posterior to the anterior segments, so that they 

 must undoubtedly be regarded as a repetition or 

 transference of the ring- spot previously developed 

 on the eleventh segment. I will now proceed to 

 furnish proofs in support of this statement. 



I have never met with any specimens having 

 ring-spots on all the segments in the most promi- 

 nent instances these spots were present on seg- 

 ments 10 5. This was the case in three out of 

 the twenty-eight caterpillars minutely examined. 

 On all these segments, however, the ring-spots 

 were not equally developed, but increased in per- 

 fection from the posterior towards the anterior 

 segments. In the larva represented in Fig. 59 for 

 example, there is a completely developed ring-spot 

 on segment 10, which, although possessing but a 

 feeble black " ground-area," is still distinctly bor- 

 dered ; on segment 9 this border is less sharp, 

 and not so dark, and it is still less sharp and 

 much lighter on segments 8 and 7, whilst 

 it has completely disappeared from segment 6, 

 the yellow " mirror " having at the same time lost 

 in size. On segment 5, only two small con- 

 tiguous reddish spots, the first rudiments of the 

 nucleus, 25 can be recognized on close inspection. 



Specimens in which the spots extend from the 

 eleventh to the seventh segment are of more 



25 The fading of the red anteriorly has not been represented 

 in the figure. 



