46 GROTE—THE DESCENT OF THE PIERIDS. [Jan. 9, 
since butterflies were butterflies, whose story is forever in the changes 
of their wings. 
The following two genera represent generalized types as compared 
with the preceding, #2 being in original position. 
Gen. /xzas Hiibner, 1816. 
Type: I. pyrene. 
Ixias pyrene, 
Radius four-branched; Ar and 2 arising above cell; 73 a 
moderate fork out of R4 + 5. Discal cell closed. d/1 ascending 
radius for a short distance beyond cross-vein; 4/2 radial. Second © 
anal sinuate with a strong fork at base. Hind wings with humeral 
spur pointed, turned to apex of wing; lower portion of discal cross- 
vein weaker, joining J72, which appears continuous. 
More specialized than the allied /dmazs and Teracolus by Mx 
being further removed from cross-vein out of radius. The genus 
may not be correctly placed, but would fall in here from the stage 
of specialization. 
Gen. Zronia Hiibner, 1822. 
Type: E. cleodora. 
Erontia cleodora. 
Radius five-branched; Ar and 2 in original position above 
cell; 3, 4 and 5 near together before apices. Discal cell closed ; 
Mi not ascending radius, but leaving at upper angle of cell. Hind 
wings with humeral spur pointed, turning to apex of wing; discal 
cross-vein joining JZ2. 
I have little doubt that this generalized type with five-branched 
radius represents an ancestral phase of Awrema and allies. 
Typical ‘‘ Yellows.”’ 
(Eurymini. ) 
As formerly pointed out by me, there seem to be two terminal 
lines, which appear to fuse and are probably also connected with 
the Euremini. 
Gen. Eurymus Swainson, 1829. 
Type: E. hyale. 
Eurymus hyale. Mitt. a. a&. Roem. Mus., 8, Taf. ii, Fig. 7 (neu- 
ration). 
Radius four-branched ; 2 has abandoned its original position 
and advanced along radius to considerably beyond cross-vein. 
