XI 



a way as shows unmistakably the progress of an evokitionary process of alteration 

 and which makes it impossible to attribute it to accident or to external influences. 

 And therefore when we meet that black in other butterflies in a way which 

 completely gives back one of those stadia of colour-evolution, occuring in the 

 numerous forms of P. Dardanus Brown, we are without doubt justified in 

 explaining it in the same manner. Such is the case f. i. in the South American 

 species Papilio Deileon Felder and the African Pieris Calypso Drury, which 

 both show the peculiar black hooked stripe of the above mentioned form Meriones 

 Felder 9 and which therefore undoubtedly happen to be in the same stage of 

 colour-evolution. This same stripe is also met with in several of the Java 

 Pieridjc mentioned hereafter ; it is, however, not always so coherent, nor does 

 it always form such a rectangular hook, but sometimes it is more or less rounded ; 

 it is, nevertheless, always to be unmistakably recognized as the same phenomenon 

 of evolution. So we sometimes also see a peculiar black little stripe on the 

 upperside of the fore-wing in the interspace between two of the veins near the 

 terminal margin as a beginning of the accretion of the black ; this is the case 

 f. i. in the 9 of Pieris Nero P., but also in other species as in some specimens 

 of Pieris Nerissa F. (See the figure by Cramek, pi. XLIV, fig. a). It is 

 true that the stripes do not always occur between the same veins nor have they 

 always the same shape, but they always show so much in the same manner 

 and all of a sudden, as it were, that it is evident that they arise from the same 

 cause. When this process proceeds further, there arise more of those stripes 

 at the same place in the interspaces between other veins, which afterwards unite 

 into a band; suchlike facts, incorrectly generalised, have probably led Eimer 

 to his well-known theory about spots and stripes. There where this hooked 

 stripe has been developed, it also happens that the black begins to form a 

 projection from exactly the opposite side of the wing, namely from the terminal 

 margin, which gradually unites with the black of the hook and in this way 

 shuts off the apical part of the wing, till the black spreads everywhere and 

 fills this part. Another time the increase of the black takes place more regu- 

 larly from the apex towards the basis of the fore-wing, or sometimes along the 

 margins. Among the Java Pieridae the black is generally much more developed 

 in the 9 than in the d, and often in such a way that the sexes can easily 

 be recognized, as f. i. either by the black on the upper-side of the fore-wings, 

 as in T. Belisama Cram., C. Scylla L., C. Chryseis Drury, and others, or 

 by this colour as a border on the upper-side of the hind-wings as in T. Hecabe L. 

 and T. Sari Horsf. So there is no question of a secondary sexual charac- 

 teristic, but only of a dissimilarity in colour-evolution, and probably in this way 

 that the c? are further advanced; as the black in these species, most times at 



