a 
1900.] GROTE—THE DESCENT OF THE PIERIDS. 39 
type, which must stand, although seldom used in this manner.’’ 
(Hist. Sketch, 255.) 
Gen. Zetracharis Grote, 1898. 
dype.) Boycethura Keld: sp: 
Tetracharis cethura. Proc. Am. Pui. Soc., xxxvii, Pl. 1, Fig. 2 
(neuration), 
Radius four-branched ; second radial branch arising before the 
cross-vein, although removed outwardly close to it. As this vein 
is shifting, it may be that this genus belongs on the other line as an 
antecedent, more generalized form to AZzdea. It is thus not an ideal 
link between Zuchloe and Pontia, but it comes near to being one. 
Gen. ELuchloe Hiibn., 1816. 
Type: E. cardamines. 
Liuchloe cardamines. Mitt. a. dad. Roemer Mus., 8 Taf. ii, Fig. 9 
(neuration). 
Radius five-branched ; second radial in original position. This 
is the generalized form of the group, with the second radial 
branch not removed outwardly toward the cross-vein. Hence it may 
represent an ancestral form of Ponta daplidice, with Tetracharis as 
possibly marking an intermediate four-branched stage. 
Euchloe stella. 
Radius five-branched ; second radial in original position. As 
compared with cardamines it agrees in essentials. It differs in that 
the fork 4 is a little shorter and that there is a trace of a back- 
ward spur on the short and here not oblique cross-vein between 
M2 and radius. Else I can find no difference and conclude the 
forms to be congeneric. 
We now come to the lateral line, in which the second radial has 
shifted to the Z7zfurcu/a position, opposite the cross-vein and then 
beyond it. I reverse here the order and commence with the most 
generalized form, comparable with Zuchloe. 
Before going further I wish to say a word upon the humeral spur 
(precostal spur) of secondaries or its remnant. ‘The truncated hu- 
meral spur rises oftenest at right angles. It is then not always easy 
to say which way it tends, yet it shows an inclination to curve 
either way in special cases. Whether we can lay astrong deter- 
minative value on the directions we now perceive is to me doubtful. 
