Phylogeny of the Pierinee. 273 
but in this insect the black markedly predominates. 
The discoidal spot in the forewing of R. leachiana is also 
noticeable as having a small companion, of similar 
character but with a greater proportion of orange, 
the root of the interspace between the subcostal and the 
first discoidal nervure. 
The discoidal spots in Dercas, when present, corre- 
spond closely with those in the genera just named. The 
spot on the forewing of D. lycorias is like that in 
G. rhamni; it is, however, less compact, and surrounds 
both disco-cellular nervules instead of the second only, 
as in the latter insect. The spot on the upper surface of 
the hindwing is scarcely visible, but those on both wings 
beneath nearly resemble the corresponding marks in 
R. leachiana. On the underside of D. wallichit the 
_ marks are of the same character, but reduced in size ; 
from the upper surface they are almost or quite 
absent. 
In Meganostoma the discoidal spots, both above and 
beneath, so closely correspond with those in Colias as to 
call for no special remark. In Callidryas, Metwra, Pheebis, 
Aphrissa, and Catopsilia, they present also the same 
general appearance. On the upper surface of the hind- 
wing, the discoidal spot is seen as a rule faintly or not at 
all; but on the forewing there is often a well-marked 
dark patch, enclosing either the second disco-cellular, 
as usually in Catopsilia thauruma and C. catilla ¢, 
or both disco-cellulars, as in Aphrissa godartiana 2. On 
the underside the form of a silvery circular patch, 
surrounded by a pinkish or brownish ring, is almost 
universally kept up. There ig in some species (as in 
Callidryas philea) a tendency for the discoidal spot in 
the forewing to divide into two parts, one for each disco- 
cellular nervule ; while in the hindwing the small com- 
panion which has been already noticed in Colias is nearly 
always present in the interspace between the discoidal 
and subcostal nervures. One or two species (as C. 
jlorella 2) possess a second companion within the cell. 
The present series, when fully resolved, seems thus to 
consist of five spots, two belonging to the two disco- 
cellular nervules in the forewing, the third belonging to 
the interspace between the subcostal and _ discoidal 
nervures in the hindwing, the fourth to the second 
disco-cellular nervule, and the fifth to the discoidal cell, 
