50 
Parnassi-Papilionide. All changes of position by the moving veins 
should be noted and appreciated through comparison. 
Having thus attained in outline a general knowledge and con- 
ception of the direction of specialisation in the wings of the 
Lepidoptera as a whole, let us apply it cautiously to a single group, 
the day butterflies. On comparing all these forms it becomes at 
once evident that these directions, above described by me, arise 
independently on different lines of general structure and probable 
descent. They are therefore to this extent secondary. We are not 
to throw all the three-branched forms and all the five-branched 
together, which is what would be perhaps done by uncritical 
students. Along with all the other general points of agreement 
the evolution of the neuration goes hand in hand. It claims in 
classification no preponderant part, but one of equal consideration. 
A system must be sought which will avoid contradictions from any 
side. 
Perhaps a clear example of the secondary value of the neuration 
is offered by the suppression of the radial veins in the Parnassiide, 
the Lyczenidz, and again in the Pieridae. This direction is taken 
identically in separate groups not otherwise nearly related, or possibly 
arising directly together, just as (and I agree here with my excellent 
friend Dr. Chapman) the abbreviate male fore-leg has plainly deve- 
loped itself independently in the Blues from the appearance of a 
similar but more developed abortive structure in the Nymphalids. 
The ancestors of both we safely assume to have been possessed of 
six unabbreviated legs, but their common ancestry is a remote one. 
In the same way the suppression of the radial veins has commenced 
independently in the Parnassians, in the Whites, and in the Blues, 
these groups having all clearly possessed a five-branched radius, as is 
proved by its present retention and occurrence in many of the 
existing generalised forms. ‘The Pierids, as is shown by the general 
fashion of the wing, represent rather a continuation of the main or 
Nymphalid-Hesperid stem, the Blues a development of the specially 
Hesperid branch, as I judge from the same considerations, the 
grounds for this view being given in some detail in my “ Butterflies 
of Hildesheim.” 
That the action is unequal, sometimes hastened, sometimes 
retarded, that the same wing presents in its different parts a different 
degree of specialisation, we can see by the particular study of Papc/ro. 
On the primaries the radius is five-branched, and thus generalised 
as compared with Parzass‘us. ‘The media and the medial system is 
generalised by the closed cell and central position of the middle 
branch ; on the secondaries the middle branch already yields to the 
cubitus, and is therefore here more specialised. Whether the curved 
internal vein of primaries is a generalisation or not is uncertain ; 
it may be admitted as probable. On the hind wings the suppression 
of vein VIII on the internal margin is a distinct specialisation over 
all the other butterflies. From the neuration, then, the Parnassi- 
