1900. ] GROTE—THE DESCENT OF THE PIERIDS. 43 
angles, which, in a branch of the typical line, become unusually 
prominent, more so than in the angled Whites. No characters 
have been found to separate these lines, which possibly interlace. 
The antennz seem relatively shorter, the thorax more pilose and 
the body stouter in the typical line, but these distinctions are rela- 
tive and cannot be controlled. 
Non-typical Yellows. 
(Euremini.) 
Gen. Wathalis Boisduval, 1836. 
Types Ne role. 
Nathalis tole. Grote, Proc. AM. Pui. Soc., xxxvii, Pl. i, Fig. 5 
(neuration). 
Wings entire; radius three-branched; 1 in original position ; 
Fz advanced outwardly to extremely near cress-vein, hence the 
Trifurcula position is practically assumed. Discal cells on both 
wings broadening outwardly; J/1 ascending radius outside of 
discal cell for a space a little less than one-third of the distance to 
external margin. On fore wings J/2 is nearly central, on hind 
wings radial. A trace of fork to second anal on primaries. On 
secondaries the humeral spur has vanished, leaving the outer edge of 
the vein simply a little uneven or jagged. This is the most ad- 
vanced form and a specialization of Hurema. In my figure, other- 
wise quite exact, the slightly jagged edge to subcostal is not, it 
hardly can be, rendered. 
Gen. Eurema Hiibner, 1816. 
Type: E. delia. 
Eurema delta. 
Wings entire; radius four-branched ; “1 in original position ; 
2 advanced, but much further from cross-vein than in Vathalts ; 
R3 a rather long furcation out of R4 + 5. Af ascending 
radius but not so far as in Vathalis; M2 nearly central on both 
wings. On secondaries the humeral spur has vanished leaving the 
vein apparently a trifle more jagged than in WVafhalis. The cross- 
vein joins J/rt on hind wings, whereas in /Va/¢ha/zs it nearly meets, 
as On primaries, the radius. 
If anything were needed to prove the reality of the successional 
movements in specialization of the veins on the butterfly’s wing, as 
