“I 
1900. | GROTE—THE DESCENT OF THE PIERIDS. 
scheme. Let us first take up the wings of some moths and show 
by comparison that they may be more specialized than those of the 
butterflies. 
Specialization is shown by the different groups of the diurnals in 
a variety of ways and directions. It may be said of the Papilio- 
nides, that their main advance is in the reduction of the anal veins 
of hind wings and the hollowing out of the internal margin of the 
wing, as shown in an extreme degree by Parnassius. Now, when 
we examine the wings of the Saturnians, we see, in such genera as 
Rothschildia, Samia and Callosamia, the number of anal veins 
equally reduced to one, the internal margin equally hollowed out. 
It may be said again of the Pierids, that their main advance is 
shown by the diminution of the branches of the radius of the fore 
wings, which from five in number are reduced to four and three. 
Turning back to Rothschildia, Samia, Attacus, etc., we find the 
same reduction. It may be said in turn of the Nymphalids, that 
their main advance is shown by the opening of the discal cell, the 
more complete disintegration of the median system of neuration. 
Again in the same genera of Attacinee, we find the cell even more 
completely open, the cross-vein vanished, the centre of the wing 
longitudinally clean from veins, the median system completely divi- 
ded between and absorbed by the radius and cubitus (see my 
figures of Saturnian wings: Bestrag zur Classification der Schmet- 
terlinge). Thus the wings of the single Attacid genus Rothschit- 
dia combine in a high degree the main features of the specializa- 
tions shown separately by three most important groups of the 
diurnals. The Attacid wing is far more specialized than the wing 
of any butterfly. Not only this, it has also lost all residual features 
which are retained by the butterflies. Let us enumerate some of 
these: The backward spurs, traces of the base of the median sys- 
tem, to the discal cross-vein, present in many butterflies, are lost. 
All trace of the cubital cross-vein has vanished from the Attacid 
primary. This is strong in Pago and allies, quite marked in a 
number of Nymphalid forms, Morphide, Limnadidez, Heliconiide. 
On the hind wings, the humeral cell, formed by the forking of the 
radius, closed by the residuary vein Ri, has also gone. This is 
found, in various stages of completeness, in many butterflies. The 
humeral spur (precostal spur) of the butterflies has disappeared in 
the Saturnians, while the frenulum has departed in both groups. If 
we take the specializations as indicating younger forms, then the 
