286 Dr. Frederick A. Dixey on the 
In those species of Pieris (such as P. habra and 
P. locusta) which present on the underside of the hind- 
wing a pattern only slightly modified from that of 
Leodonta and Catasticta, the red basal marks are clearly 
to be distinguished. A bright red patch characterises 
the inner division of the precostal space, and in most 
specimens is also prolonged into the outer division, while 
the apices of the median and internal spaces are likewise 
provided with conspicuous red touches. Comparing 
the underside of P. locusta with that of any of the 
American mimetic forms of Mylothris, we cannot well 
resist the conclusion that the central horizontal red or 
chestnut band in the latter species represents the touches 
of red in the median and internal spaces of P. locusta. 
The relation is best traced in the case of M. lypera, in 
which insect the part played by the yellow streak of the 
costal interspace in the production of the mimetic 
pattern is also clearly to be seen; but other species, such 
as M. lorena and M. pyrrha, whose mimicry of Heli- 
conine forms is further advanced than that of M. lypera, 
still show the origin of the central red band almost 
equally well. In Hesperocharis hirlanda a somewhat 
similar effect is produced by slightly different means. 
The basal red is here confined to the precostal and 
internal spaces, not being found (as in Pieris) in the 
median. The horizontal red band is therefore not 
central but costal, its mnermost extremity being con- 
stituted not (as in Mylothris) by the red patch of the 
internal space, but by that of the mner division of the 
precostal. The whole of the precostal red, which is 
absent in the three species of Mylothris just referred to, 
is prominent in H. hirlanda. Although these differences 
involve a change in the relative position of the horizontal 
bands of red and pale yellow in the latter species, yet 
the general resemblance of the underside to that of 
M. pyrrha ¢ is considerable, and is probably quite 
enough to tell perceptibly in the insect’s favour. Other 
species of Hesperocharis, which are unaffected by 
mimicry, show the basal marks in the same position, 
but, as a rule, not very definitely, except at or near the 
root of the precostal space. Here there generally 
occurs an orange spot which partly represents the red 
precostal patch in H. hirlanda (see H. nereis, H. mar- 
chalii, and H.anguitia), but which in some species (as 
