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MARCH gth, 1899. 



Mr. R. Adkin, F.E.S., in the Chair. 



Mr. Main exhibited two specimens of the sea-spider 

 (Pycnogonum littorale), taken crawling on wooden piles in 

 the Medway at Port Victoria. The sexual organs of this 

 creature are situated in both sexes in the fourth or fifth joint 

 of the legs, so that there are eight of them. In the females, 

 however, the eggs are extruded from an aperture in the second 

 joint. 



Mr. Adkin exhibited male imagines and cases of Psyche 

 villosella, from Bournemouth ; also a case of P. opacella, 

 from Aberdeenshire. 



Mr. Stanley Edwards exhibited cases of and females of 

 Psyche villosella, P. graminella, and P. opacella, all from Fon- 

 tainebleau. 



Mr. Tutt communicated an interesting paper on " The 

 Nature of Metamorphosis " (p. 20), and a short discussion 

 ensued. 



MARCH 23rd, 1899. 



Mr. J. W. Tutt, Vice-President, in the Chair. 



The following communication from Mr. T. D. A. 

 Cockerell was read, with a request that the ideas therein 

 expressed might be discussed by the Society : — 



An examination of Skinner's Synonymic Catalogue of 

 North American Rhopalocera, published in 1898, recalls 

 and emphasises certain interesting features of our butterfly 

 fauna. Certain portions are of tropical origin, while other 

 groups belong to what has been called the holarctic region. 

 In the tropics conditions have been relatively uniform for 

 ages, and in consequence we have a large number of 

 organisms in a condition of considerable stability — in other 

 words, " good species." 



The writer has found, when working with Coccidae, that 

 the tropical species are, as a general rule, much more easily 

 separated than those of temperate regions. The same is 

 true, apparently, among the butterflies. Take the Hespe- 

 ridse and Lycaenidae, which are so numerous in tropical 

 America. The tropical groups of Hesperidae, in particular, 

 have largely invaded the United States, and very many 

 species have been catalogued. Now Dr. Skinner himself 

 has told us in another connection that these species are, as 



