1900. ] GROTE—THE DESCENT OF THE PIERIDS. 49 
cal cross-vein medially degenerate, joining J/2 immediately be- 
yond the furcation of J/2 with 473. This species, with sickle- 
shaped outer margin of primaries and pointed apices between 
#4 -+ 5 and J/1, with also angulate secondaries at Cr, is more 
specialized than Rhodocera, and lags behind Amynthia in the 
position of #2. Since I use the type for comparison I describe 
it first; on the whole it seems the more specialized genus. 
The generic terms Gonepteryx Leach, 1815, and Aarina Speyer, 
1839, are considered by Mr. Scudder as synonymous with Colas 
Fab., nec Auct., as also Gonoptera Dalman, in Billberg, 1820. 
Gen. Amynthia Swainson, 1832. 
Type: A. merula. 
Amynthia merula. 
This type shows a stage in which 2 has progressed further 
along radius than in Cofas, stopping but little before cross-vein. 
On the other hand there are jagged points showing the trace of the 
humeral spur, which I do not see in Coéas, and the position of 472 
on secondaries is more central from cross-vein and more gener- 
alized, being as-in Rhodocera. The specializations are, as I have 
constantly stated, unequal. The apices of fore wings are less sharp 
in Amnuythia, which, aside from the movement of #2, is more 
generalized than Codzas. 
Gen. Rhodocera Boisduval, 1829. 
Type: R. menippe. 
Rhodocera menippe. 
This form differs from the preceding in the absence of angula- 
tion to hind wings and the blunt primaries, with external margin, 
but little depressed. It is the more primitive of the three forms, 
agreeing with Amynthia in the position of 472 and approaching 
Colias in the position of Az. It is more generalized than either 
in the fact that the base of the humeral spur still remains. This 
large butterfly represents a stage which both Colas and Amynthia 
have, in varying degrees, abandoned. 
We will now take up an angulate type, which is more specialized 
than Rhodocera, which it resembles in shape of primaries, and in- 
termediate between Cofas and Amynthia in position of 72. 
PROC. AMER. PHILOS. SOC. XxxIX. 161. D. PRINTED MARCH 24, 1900. 
