( ii ) 



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.fi., between Pier Is locusta 3 and Heliconius 

 rydno, and it must therefore be concluded that the Pierid was 

 inedible, a conclusion previously reached in the case of other 

 Pieridae 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 Miil- 

 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 

 single species such as P. locusta were drawn apart into more 

 or less intimate relationships with separate Miillerian groups. 

 Mr. Blandford then exhibited and described the series of 

 Neotropical butterflies from the Godman-Salvin collection, 

 which were shown by him on a previous occasion (Proc. Ent, 

 Soc. Lond., 1896, p. xxxviii.) ; he stated that he used the 

 term " homceochromatism," originally employed in the 

 "Biologia Centrali- Americana," in preference to Dr. Dixey's 

 term "reciprocal mimicry," to denote the phenomenon 

 exhibited by " Miillerian " groups, because it gave a sufficient 

 indication of its nature without assuming any theoretical con- 

 sideration as to its origin. The series shown were : — 



I. HOMCEOCHROMATISM BETWEEN PaiRED SpECIES OF THE SAME 



Genus. 



Heliconius gaJanthus and H. luce. Guatemala. 



H. chioneus and H. sappho. Panama. 



H. cydno and R. eleuchia. Colombia. 



H. alithea and H. primularis. Ecuador. 



Each pair was closely alike on the upper-side ; the under- 

 sides were different, there being common types for the right- 

 hand and left-hand members of the pairs respectively. 

 There was also a progressive modification in the patterns of 

 the upper-side in proceeding from North to South. 



