(cc) 
ship with Fleliconius atthis; the series represented by P. pax- 
dosia and P, leptalina, which approached Napeogenes inachia ; 
the series dealt with in a previous communication (Trans. 
Ent. Soc. Lond., 1896, pp. 65-79), which led up to forms 
associated with Heliconius numata; and lastly, a series 
derived from the one last-mentioned, which ended in 
Mylothris alethina 2, a mimic of Tithorea tarracina. 
In all these instances, the model towards which the series 
tended did not present an isolated scheme of colour, but was 
a member of a larger or smaller group of forms, associated in 
external features; such as were shown in the series to be 
exhibited by Mr. Blandford. These mimetic groups were no 
doubt mainly of the ‘Miillerian” kind, that is, they were 
associations between inedible species of various affinities. 
Reasons were given for attributing great importance to the 
operation of the Miillerian principle in producing such a 
facies as that of the neotropical fauna, and for assigning to 
Batesian mimicry a comparatively subordinate position. Stress 
was laid on the facts (1) that Batesian mimicry could exist 
only when the numbers of the mimic were insignificant 
compared with those of the model, whilst a Miillerian group 
was strengthened by every fresh accession; and (2) that the 
attractive power in Batesian mimicry acted only from the 
model towards the mimic, whereas in Miillerian association it 
was mutual, and tended to produce reciprocal changes. For 
this mutual modification of characters the term “reciprocal 
mimicry ’’ was suggested. A relation of the latter kind 
appeared to exist, e.y., between Pieris locusta ¢ and Heliconius 
cydno, and it must therefore be concluded that the Pierid was 
inedible, a conclusion previously reached in the case of other 
Pieride on more than one kind of evidence. A consequence of 
the keen competition for life in such a region as the neotropical 
was that scarcely any conspicuous form was completely isolated. 
If edible, it would generally be a Batesian mimic; if nauseous, 
it would be drawn into the vortex of one of the great Mul- 
lerian groups. The force exerted by these latter was well 
exemplified by the facts dwelt upon at the beginning of the 
paper, which showed the steps by which the members of a 
single genus such as Pieris, and sometimes even the sexes of a 
