( xcvii ) 



occurrence of the two species, which tend to strengthen 

 the conclusion that the Colaenis, so far from being relatively 

 rare, as we should expect, of a Batesian mimic, is probably 

 commoner than the Heliconius. Collections received by Mr. 

 Rosenberg from three different localities contained altogether 

 76 of the Colaenis and 73 of the Heliconius. The numbers 

 were distributed as follows : — 



El Huanca- 



Porvenir. Pozuzo. bainba. 



Colaenis .... 12 32 32 



Heliconius .... 56 — 17 



There was no reason, so far as Mr. Rosenberg is aware, for 

 the collectors to have given more attention to one species than 

 to the other. 



" There appears to be no doubt that the Colaenis is the 

 commoner insect in dealers' stocks. Mr. Rosenberg has also 

 sent me some figures which show that one dealer charges 

 nearly three times as much for the Heliconius as for the 

 Colaenis ; another charges twice as much ; and a third has a 

 stock of the Colaenis, but does not list the Heliconius at all. 



" It is hardly to be expected that a Batesian mimic should 

 be as common as, and even less to be expected that it 

 should be commoner than, its model ; still more improbable 

 does it seem that the Batesian mimic should occur in places 

 from which its model is absent. This is one reason why I 

 am inclined to think that the mimicry of Mylothris agathina, 

 Cram., by the dry-season form of Belenois thysa, Hopff., is 

 Miillerian rather than Batesian. In a morning's collection 

 at Congella, near Durban, Natal, in 1905, Dr. Longstaff and 

 I found B. thysa not uncommon ; but M. agathina was not to 

 be seen, though we were on the look-out for it for purposes of 

 scent-extraction. This observation is confirmed by a record 

 in the Entomologist, vol. xli, 1908, p. 31, where Mr. H. W. 

 Simmonds says that at Stella Bush, Bei-ea, Durban, on 

 March 5, 1907, ' one of the commonest butterflies was Pieris 

 [Belenois] thysa, but, strange to say, its model, Mylothris 

 agathina, was quite scarce.' Mylothris agathina is no doubt 

 generally the commoner form, but there ai-e evidently times and 

 places when it has to yield in point of frequency to its mimic 

 Belenois thysa." 



