484 Mr. G. A. K. Marshall on 



corresponds to the bar itself. The comparison to a pseudo- 

 morph suggests itself; the bar is indeed absent but its 

 shape is there. The case of the Acrseine mimic is still 

 clearer, Figs. 8 and 3a on Plate XIV bearing the same 

 relationship as that above described in vMrshal/i-dohrii//i, 

 to Figs. 8 and 2a on Plate XV. The same " pseudo- 

 morph " of the white bar can be seen in the latter, while 

 in Figs. 4, 5, and 6, on Plate XV, some by no moans un- 

 common intermediate varieties between enccdon and daira 

 are represented. Fig. 7 shows the form alcip^mia which 

 resembles alcippus, the white-hind-winged chnjuipinis. 



When a geologist finds a recognizable fragment of one 

 rock included in a stratum of another, he is usually safe in 

 inferring that the latter is the younger. With equal 

 confidence the zoologist may conclude that the mimicking 

 species is younger than the species it mimics. The latter 

 must have been in existence before the former attained a 

 resemblance to it. From this point of view the comparison 

 between chrysijij^us-l'Inr/ii and their mimics is of intense 

 interest. Gkri/sijjjnts and hlugii are now well defined the 

 one from the other, and it is probably impossible or at 

 least extremely difficult to get a series of intermediate 

 forms between them. If we liad not the mimics we might 

 well believe that hhigii arose ready-made from eho'ysijjpvs 

 by a process of discontinuous or transilient evolution. 

 But two of the younger mimics are very common and 

 widespread, and both misijypns-inaria and cncedon-daiva 

 present us with abundant varieties showing every grade 

 of transition from the one form to the other. Of the 

 Lycpcnid less can be said. It is still extremely rare (see 

 pp. 472, 478) and at present only known in two widely- 

 separated areas. But even in it tlie gap marshaU i-dohcrtyi 

 has been shown above to be much less wide than that of 

 chrysippns-ldngii. We are led to believe from this com- 

 parison tliat in some earlier age the two forms of the 

 Danaino model existed in the stage now reached by their 

 commonest mimics, and, like these, were connected by a 

 series of abundant intermediate varieties which have since 

 been obliterated by selection. 



E. Aiiiauris ccheria-like Group : Marked Secondary Beseiji- 

 blances between the Forms mimicking echeria. 



This species of Amanris, with its very characteristic 

 rectangular buff patch on the hind-wing and buff or white- 



