Phylogeny of the Pierine. 319 
Old World by Delias, Prioneris, and Metaporia, is never- 
theless of high importance and very great interest. 
The first departure from the condition of Catasticta 
seems to be that taken by the butterflies of the genus 
Pieris as restricted by Butler, closely associated with 
which must come the American species of Mylothris. The 
underside of Pieris locusta exhibits a pattern which is but 
little removed from that of Catasticta, the yellow streaks 
and red basal patches being still apparent on the under- 
side of the hindwing; while the upper surface of both 
wings is shared between the original dark and intrusive 
light ground colour in much the same manner as in C. 
ctemene, C. corcyra, and other species of Catasticta. In 
Pieris as a whole, the dark ground-colour has to a great 
extent disappeared from the upper surface; several 
species however (as P. pylotis and P. bunie) retain a 
discoidal spot in the forewing, which in some, as P. 
thaloe 2, is connected with a dark streak along the costa, 
and in others, as P. demophile 2, is included in a larger | 
remnant of ground-colour which passes as a dark fascia 
obliquely across the wing from the costa to the outer 
border. The underside of the hindwing in this genus 
tends to lose the Catasticta-like character preserved in 
P. locusta, in consequence of a general paling which takes 
effect first in the basal half and spreads outwards (as in 
P. demophile), until in such species as P. bunice it reduces 
the wing to very much the same condition as that seen 
in Ganoris brassice or G. rapi. The ground-colour in 
P. buniew and P. pylotis is indeed even paler than in 
these species of Ganoris, being without the powdering of 
black scales which the latter possess; the hindwing 
however of both P. bunie and P. pylotis retains a dis- 
coidal spot, and, as has been already noted (pp. 287, 289, 
note), the predominance of the paler colouring is never 
so great as not to leave unmistakable relics of the yellow 
streaks and red basal patches. 
The genus Leptophobia appears to be a kind of con- 
tinuation of Pieris. The arrangement of light and dark 
ground-colour preserves a parallel course im the two 
genera, and the inclusion of the discoidal spot of the 
forewings in a dark fascia which passes from the costa 
for a greater or less distance obliquely towards the outer 
margin is a common feature in Leptophobia as well as in 
Pieris. In the present genus the underside of the hind- 
