50 GROTE—THE DESCENT OF THE PIERIDS. [Jan. 5, 
Gen. Dercas Boisduval, 1847. 
Type: D. verhuellii. 
Dercas verhueltit. 
Primaries blunt, external margin uneven ; not depressed ; sec- 
ondaries angulated just beyond 473. ‘Texture of the wings frail 
as compared with Co/as and allies. Radius four-branched; 2 
has advanced to almost exactly opposite cross-vein, thus the 7Z77- 
furcular position is very nearly assumed. Else the venation is 
much as in Amynthia, M2 a little more radial. Hind wings, with 
humeral spur developed, but feeble, pointed, curving a little to 
base of wing. 
This form has evidently the same parentage as the preceding, 
but represents a slightly differing type of wing. 
We now arrive at three types, which are really too close to be of 
much interest to the classification, and which stand in the relation 
of ancestral forms to the foregoing modified types with angulate, 
leaf-shaped wings. I take the genera in the order of priority. 
Gen. Catopsitia Hiibner, 1816. 
Type: C. crocale: 
Catopsilia crocale. 
Wings entire; radius four-branched ; #2 advanced almost to 
Opposite cross-vein, not quite so near as in Dercas. Discal cell 
closed ; J/1 from radius, about as far advanced along the vein as 
in preceding genera; d/2 from cross-vein, radial, nearly in the 
position of preceding genera. Second anal with fork at base. The 
humeral spur is present as a basal fragment. 
This series shows the progression of J/1 up the radius, in Catop- 
stdia the most advanced. The genera on the whole lag behind the 
preceding, not only in the non-angulate, normally shaped wings, 
but as affording evidence that the Co/vas types have sprung from 
such forms in the retarded characters of the venation. 
Gen. Phedbis Hiibner, 1816. 
Type: P. argante. 
Phebis argante. 
As compared with Cafopsilia the ascent of J/1 up the radius is 
retarded ; the fork of R3 with R4-+ 5 is somewhat longer, all 
characters of comparative generalization. In fact these three types 
