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from the last meeting was resumed, Mr. H. Rowland-Brown 

 raising the question of the probable meaning of the apparent 

 mimicry of the two species. The Eev. G. Wheeler com- 

 menting on Mr. Tutt's statement that as a rule the two 

 species in the lowlands are rarely, if ever, common together, 

 remarked that at Berisal they often occurred simultaneously 

 in vast numbers, though P. argyrognomon would sometimes 

 be a full month before P. argus came on the scene. He 

 objected to the suggestion of mimiciy because there was no 

 ground for supposing that it would be of any utility to either 

 species. Mr. G. A. K. Marshall suggested that the resem- 

 blance between the species was not due to mimicry, but to 

 close relationship ; and that the differentiation into species 

 had arisen as a result of a dimorphic variation in the genitalia. 

 Dr. K. Jordan pointed out that, as was usual in such cases, 

 the differences in the genitalia were of degree rather than of 

 kind ; he considered that the two forms were certainly distinct 

 species, and could not be regarded as dimorphic varieties. 

 Mr. J. E. Collin, the President, and other Fellows, continued 

 the discussion. 



The President having invited Mr. Tutt to reply on the dis- 

 cussion, Mr. Tutt stated that he did not think that there was 

 any question of mimicry in the similar appearance of the two 

 species. He considered that the two species were really 

 closely allied, and that the great differences in the ancillary 

 appendages possibly did not denote so great a division between 

 them as might appear. He pointed out that the life-histories 

 of the two species were quite distinct, and had been known 

 quite 1 35 years. With regard to the appearance of the two 

 species together it was to be remembered that, in the low- 

 lands, argyrognomon was double-brooded and argus largely 

 single-brooded, and this did not allow of any real overlapping, 

 though there was some ; in the mountains it was true both 

 species occurred more or less at the same time, largely how- 

 ever there with argyrognomon well ahead of argus. There 

 could be no doubt about the distinction of the species ; Mr. 

 Marshall's idea of the two forming a dimorphic species had 

 nothing whatever to support it. 



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