58 GROTE—THE DESCENT OF THE PIERIDS. [Jan. 5, 
THE DIPHYLETISM OF THE DIURNALS. 
From unpublished photographs sent me by Prof. Comstock it 
appears that on primaries a bifurcate third anal vein is present in 
the pupa of Pzeris, of which no trace is seen in the imago, unless 
we consider the thin piece, anastomosing with second anal at base, 
asarelic. If the homology of the free third anal vein of the imago 
of the Papilionides, with this thin piece (sometimes a mere scar, 
again wanting) joined outwardly to second anal of the imago of the 
Hesperiades, be denied, the definition given by me (Proc. AMER. 
PHIL. Soc., xxxviii, 43) may be accepted. If, on the contrary, the 
homology be asserted, then the wording may be altered as follows : 
A. Butterflies having a short third anal vein on primaries, run- 
ning downwardly free from base of wing to internal margin ; 
on secondaries only one anal vein. . . . . .. PAPILIONIDES. 
#&. Butterflies having a short third anal vein on primaries, join- 
ing outwardly the second anal vein (this fork sometimes want- 
ing by reduction and always thinner than second-anal or de- 
generate) and having more than one anal vein on second- 
AMES. Ao -t w os Bie ad. 2 ee Ree avo eel ESPERIORS. 
The question of the homology of the veins cannot affect (as I 
have elsewhere stated) the argument as to the diphyletism of the 
diurnals. A natural group in which a certain vein is free in the 
imago cannot well have the same origin with an opposed and equally 
natural group in which this same vein runs in an opposite direction 
and fuses with the next vein lying above it. The troublesome factor 
in the classification of the diurnals has been the position of the 
Papilionides. They have been approached violently to the Pierids 
and learned treatises have allied them with the Hesperids. And 
then they have been forcibly thrust in between the Blues and 
the Skippers, an inoculation which the genealogical tree most 
naturally resists. If we succeed in removing them from their 
enforced union with the Hesperiades, unexpected light may fall 
upon the history of the development of the Lepidopterous 
organization. Nor can we fit the Papilionides in between the 
Hesperiades and the moths, so that, in a linear arrangement, 
the only course remaining open for us to pursue is to head 
with them the series of the diurnals. The whole question of phy- 
logeny isa relative one. Even if we can make out resemblances in 
