0^ Dr. F. A. i)ixey on the pKylogenetic 



therefore propose to adopt the letters and numbers I 

 have just given as a uniform means of distinguishing 

 these markings both in figures and descriptions. In cer- 

 tain forms, as for instance V. polychloros, V. io (fig. 2), 

 and the various species of the genus Grapta, they are as 

 easily recognised as in V, urticce ; in others one or more 

 may be obliterated (as A in P. atalanta, see fig. 3), the rest 

 remaining easily recognisable ; in others again some or 

 all of the patches may be broken up into separate 

 constituents, as in most members of the genus Argynnis 

 (fig. 4)5 but, as will be shown, not in such a way as to lose 

 their actual identity. When this resolution happens, I 

 shall retain the letter or number already given as the 

 collective designation of the entire group of constituent 

 markings, while generally distinguishing the separate 

 members by the Arabic numerals, 1, 2, 3, 4, &c., in the 

 case of the dark, and the letters a, j3, y, J, &c., in the case 

 of the light areas. It will be seen in the sequel that 

 in nearly every case the costal patch forms part of a 

 series of markings which belongs or did belong to the 

 entire wing, and indeed to both fore and hind wing alike. 

 It will therefore be necessary, as we proceed, to enlarge 

 the notions we have at first attached to the letters A to 

 D, and the numbers I. to IV., and to make them stand 

 for the whole range of marks, of which the most 

 conspicuously and uniformly recognisable portions occupy 

 the region of the costa. It will, moreover, in some 

 cases be convenient to introduce a further division of 

 groups into 11. and 11'., III. and III'., &c. (figs. 31, 37). 



We may now begin the consideration of the wing- 

 markings in detail, taking first — 



1. The series of light- coloured spots near the apex oj 

 the primaries. — Comparing Pyrameis carclid with P. 

 atalanta, we are at once struck with the identity of 

 pattern shown by the apex of the fore wings in these 

 species. On the black ground of this region in P. 

 cardui occur four conspicuous white spots (tig. 5, «, B, 

 7, ^) arranged in a curve, the first and fourth being 

 markedly larger than the other two. These are 

 obviously homologous with the • similar white spots 

 in P. atalanta (tigs. 6, 7), which are arranged in a 

 curve of the same character and keep much the same 

 relative size, /? and y being, however, a little smaller in 

 P. atalanta than in P. cardui, and a showing distinctly 



