( xxii ) 



professed to support Mlillerian mimicry, yet his defence of 

 Reciprocal Mimicry really constituted a severe attack upon 

 that theory. For he pointed out that Dr. Dixey had con- 

 demned certain of Mr. Marshall's contentions as vitiated and 

 valueless because they were based on inaccurate postulates, 

 whereas these postulates were the very ones which Fritz 

 Miiller himself had used. 



Mr. S. A. Neave said that as a result of his field experience 

 in Africa he was unable to accept the theory as to the function 

 of " double aposemes," but he did not mean thereby to imply 

 that he rejected every case of Eeciprocal Mimicry. He 

 suggested that Alternate Mimicry might not be so uncommon 

 a phenomenon as Mr. Marshall appeared to think. 



Mr. J. W. TuTT asked whether Mr. Marshall really knew 

 of a single instance in which two species, supposed to carry 

 different aposemes, lived in the same place with another 

 species that showed the double aposeme of these species, and 

 occurred with them at the same time. He remarked further 

 that in his exhibit Mr. Marshall showed two species with 

 different aposemes living in Peru, together with the presumed 

 species showing the double aposeme, which he noted did " not 

 occur within 1000 miles of Peru " ; was there no instance 

 known in natui-e which illustrated the point at issue, and so 

 removed the question from the rank of pure theory ? 



Mr. Marshall said that such a case was not known to him. 



Mr. W. E. Sharp and Professor T. Hudson Bbare also made 

 some brief comments on the subject. 



Wednesday, May 5th, 1909. 



Dr. F. A. Dixey, M.A., M.D., President, in the Chair. 



Exhibitions. 



Rhinoceros Oestrid Fly. — Mr. S. A. ISTeave exhibited 

 three specimens of a remarkable Oestrid fly belonging to the 

 genus Spathicera^ Corti, captured on the carcase of a rhinoceros 

 shot by him near Fort Jameson, IST.E. Rhodesia, in February 



