1900.] GROTE—THE DESCENT OF THE PIERIDS. 61 
the wings. It has been with them a question chiefly of color and 
pattern or outline. The conclusion to which these studies of the 
neuration lead is this: Zhe older and more generalized forms, 
here Nymphalids and Papilionids, serve as models; the younger 
and more spectalized forms, here Pierids and Dismorphians, do the 
copying. As yet I know of no older type which has assumed the 
dress of a younger. Mimicry would thus fall in with other phe- 
nomena of succession, and is deprived of the appearance of fortu- 
ity which now clings to it in literature. 
SYSTEM OF NOTATION. 
In the designation of the veins I have followed here the same 
system as in my other papers, with the exception that I have 
adopted Prof. Comstock’s recent change with regard to the longitu- 
dinal veins. These are indicated by an initial letter of the name 
instead of a Roman numeral. On the fore wings the subcostal is 
marked S; the radius by #, with the Arabic numerals 1 to 5 for 
the branches ; the Media by 4/1 to 3; the Cubitus by C1 to 2; 
the anal veins by 4r to 3; the third anal is wanting in the Hes- 
periades, unless the more or less illegible straight prong from the 
second anal at base be homologous with it. The costal vein is 
absent by reduction on both wings; on the primaries the thicken- 
ing of the costal edge may or may not be a trace of it, and in any 
event is of no importance to designate. On the hind wings I 
have suggested (January, ’99) that the so-called ‘‘ precostal spur’’ 
is homologous with the ‘‘ humeral veins’’ of Prof. Comstock, mul- 
tiplied inthe Lachneids. In a letter to me Prof. Comstock adopts 
this view and suggests the prong should be so notated. I prefer to 
call it the ‘‘humeral spur’’ and to mark it ‘‘h. s.’’; the word 
‘‘vein’’ might cause a confusion with a longitudinal vein. The 
subcostal of the hind wings has absorbed apparently, Prof. Com- 
stock tells me, the first branch of the radius as part of the humeral 
cell. Since this is obsolete in the present group, I have marked 
the vein here as on the primaries with a simple S. The radius of 
hind wings is reduced to a single vein, representing A2 + 3 + 4 
+ 5, the branch Axi having gone apparently with the subcostal ; 
but, since this cannot be seen in the present group, there is no use 
in complicating the notation and I use merely the letter R. The 
other veins are as on fore wings. The persistent anal vein is the 
