( 11 ) 



have only a pair from the Homeyer collection), while kahldeni 

 has more frequently been obtained in several districts. 



Professor Poultox remarked that it was extremely interest- 

 ing and inspiring to see so much new light thrown on this 

 important genus as the result of Mi\ G. F, Leigh's experiment. 



Fa])er. 



Dr. F. A. DixEY, M.A., M.D., i-ead a paper, illustrated by 

 lantern slides, " On Miillerian [Mimicry, and Diaposematism. 

 A Reply to Mr. G. A. K. Marshall." A discussion followed 

 on the whole subject, in which Mr. R. Shelford spoke in 

 favour of Mr. Marshall's views, and Professor E. B. Poultox, 

 F.R.S.jin favour of Dr. Dixey's contentions. Later Mr. G. A. 

 K. Mabshall communicated the following reply to Dr. Dixey: 

 — "Having unfortunately been prevented by illness from 

 attending the reading of Dr. Dixey's long-expected paper in 

 Ixxi] 



reply to my criticisms of his hypothesis of Diaposematism, 

 it is obviously impossible for me to make any adequate 

 rejoinder at present. But there is one point to which I 

 should like to reply immediately. When my paper was read 

 in March last, Dr. Dixey in the course of the few remarks 

 that he made afterwards stated that I had 'given myself 

 away rather badly ' on one or two points, though the nature 

 of my supposed blunders was in no way indicated. I now 

 learn that the principal point upon which I am supposed to 

 have ' given myself away ' is that I have assumed that it is 

 an essential feature of the hypothesis of Reciprocal Mimicry 

 that the two inedible forms should mimic each other simulta- 

 neoxhsly. Now, I understand that this suggestion is repudiated 

 by Dr. Dixey, who further claims that the hypothetical kind 

 of mimicry which I have called Alternating Mimicry (Tr. Ent. 

 Soc. 1908, p. 103) is merely part and parcel of his own 

 hypothesis of Diaposematism. I may here explain that the 

 idea of Alternating Mimicry is based on the supposition that 

 where two inedible species of practically similar distasteful- 

 ness are mimetically associated then the mimetic approach 

 will be in one direction only, and wiU be determined by the 

 relative numbers of the two forms. If A be numerous 

 and B much less so, then B will mimic A ; and if sub- 



