DIPHYLETISM IN THE LEPIDOPTERA. 



123 



The specialization of media is determined by the position of 

 the second median branch. Its central position is the original, 

 generalized state ; it moves by being either drawn upwards and 

 joining the radial, or downwards and then joining the cubital 

 system of the wing. The specializations of the radius have been 

 elsewhere fully discussed by me. 



In the genealogical tree published by Sir George Hampson 

 (1898) the Pierids are represented as having given rise to the 

 Nymphalids and Satyrids. In their present condition the Pierids 

 could not have done so, since the mass of forms have undergone 

 a reduction of the radius, and are thus more specialized than the 

 brush-footed butterflies, in which no such reduction has taken 

 place. It is rather probable that the Pierids and Nymphalids 

 are subparallel converging groups. The Pierids represent the 

 main ascending six-footed stem, out of which the brush-footed 

 butterflies proceeded probably as a side-issue, not as the culmi- 

 nation depicted by Sir George Hampson. The idea that the 

 butterflies are represented by groups which run together, con- 

 verge, we gather, with much other which is valuable, from Dr. 

 Chapman. I adopt it to the exclusion of the Papilionides. I 

 must also decline to accept the isolation of the skippers under a 

 separate title, which would obscure their phyletic relationship to 

 to the Lycsenids. There will probably be no other differences in 

 our views, which must be, to me, a source of congratulation. 



In shortest phrase : all classifications and phylogenies, except 

 my own, embrace the diurnal Lepidoptera in a single major 

 group, the Rhopalocera, or separate from the rest the Skippers, 

 under some similar title, holding the two as of equal morphological 

 value. Dr. Chapman calls these same two groups — Papilionides 

 and Hesperides ; Comstock calls them Butterflies and Skippers. 

 The only variation from this course is offered by those writers 

 who allow the families of the diurnals to succeed each other, in 

 a linear arrangement, without dividing them off by any special 

 term or terms from the rest of the Lepidoptera. I, alone, divide 

 the diurnals by separating from them, not the skippers, but the 

 swallow-tails and the related Parnassians, as representing a 

 distinct and closed group, possessing exclusive classificational 

 and phyletic value, and which I call the Papilionides, or butter- 

 flies proper. And I allow of no separation of the skippers from 

 the rest of the diurnals, which, gathered together under the name 

 Hesperiades, or skippers in a wide sense, I regard as a group 

 open to the moths, or Heterocera, and as not separable from 

 these by any structural feature so strong as that which divides 

 them from the Papilionides. 



