1 80 Studies in the Theory of Descent. 



Third Stage. 



After the second ecdysis the marking and 

 colouring only undergo change with respect to the 

 eye-spots. The concavities of the crescent-shaped 

 portions of the subdorsal line become black, 1 the 

 remainder of this line at the same time losing 

 much of its whiteness, and thus becoming less 

 distinct, whilst the crescents assume the appear- 

 ance of small eye-spots (Fig 20). During this 

 stage the curved, crescent-formed portions be- 

 come prepared for complete separation from the 

 remainder of the subdorsal line ; and just before 

 the third moult the eye-spots become sharply 

 defined both in front and behind, whilst the black 

 ground-colour curves upwards, and the white spots 

 gradually become lenticular and commence to 

 enlarge (Fig. 21). 



Fourth Stage. 



The third moult takes place after another 

 interval of 5 6 days, the eye-spots then becoming 

 very prominent. The white nucleus of the front 

 spot is kidney-shaped, and that of the hind spot 

 egg-shaped ; whilst the black ground-colour extends 

 as a slender border upwards along the sides of the 

 spots, but does not completely surround them till 

 towards the end of the present stage (Fig. 21). The 



1 The deposition of black pigment may commence imme- 

 diately before ecdysis. 



