196 Studies in the Theory of Descent. 



full perfection. In C. O Idenlandice , Fabr., 1 ' and in 

 C. Alecto from India, 16 the eye-spots appear to be 

 perfectly alike on all the segments ; whilst in 

 C. Acteus, Cram., 17 and in the North American 

 C. Tersa (PI. IV., Fig. 35) they are smaller on 

 the other segments than on the fourth ; and in 

 C. Celerio, Linn., from India, 19 the size of the 

 spots diminishes from the head to the tail. 



In this group also the subdorsal line is retainecl 

 in a very variable degree. In some species it 

 appears to have completely vanished (C. Acteus, 

 Celerio] ; in others it is present as a light stripe 

 extending along all the segments (C. Alecto) ; 

 whilst in others it is retained as a broad white 

 stripe, which extends only to the fourth segment 

 (C. Tersa, Fig. 35). In species possessing eye- 

 spots, the subdorsal line is thus a very variable 

 character. It is, however, an interesting fact that 

 even in the present group, which has made the 

 greatest step forward, the subdorsal line is of 

 general occurrence, because the eye-spots in all 

 these species may have almost a similar develop- 

 ment to those of Elpenor and Porcellus. The 

 ontogeny of the tropical species would alone 



16 Cat. Lep. Ins. East Ind. Comp., PI. XIII. [Figured also 

 by Butler, loc. cit. PI. XCL, Fig. i. R.M.] 



., 16 Horsfield and Moore, loc. cit. PI. X. 



17 Ibid. [= Pergesa Acteus, Walker. R.M.] 



18 [Figured also by Burmeister, loc. cit. PI. XV., Fig. 3. 

 R.M.] 



ltf Horsfield and Moore, loc. cit., PI. XI. 



