140 [June, 



read a paper, "The Eesting Positions of Butterflies and Moths," illustratin<!; his 

 remarks with a large number of admirable lantern slides, many of them from 

 photographs taken on the occasions of the various field meetings of the Society. — 

 Ht. J. Turner, Hon. Secvetarij. 



Entomological Society of London : Wednexdaii, April ^th, 1909.— 

 Dr. F. A. DixEY, M.A., M.T)., President, in the Chair. 



Mr. R. Shelford showed a number of examples of mimetic Blatlidsf., with 

 their Coleopterous models belonging mainly to the families Coccinellidx and 

 Chrijsomelidai. Mr. H. M. Edelsten, ova of Tapinostola ftilva (in situ) laid within 

 the curled leaf of Carex paJudoxa ; also a photograph of the anal segments of the 

 ? showing the earlier appendages, from I he ventral side. These when not in use 

 are carried flat, but when the ? is going to lay, they are folded together and thrust 

 between the curled edges of a leaf to force it apart ; the fold makes a hollow in which 

 the ova are deposited ; and the leaf closes over the ova when the appendages are 

 withdrawn. The discussion on the two similar species, Plebeiun argux and P. orgi/- 

 rognomon was resumed and concluded. Mr. G. A. K. Marshall suggested the 

 possibility of their being a dimorphic species, bnt Dr. K. Jordan pointed out tliat 

 this was impossible owing to the very different nature of the genitalia. The Rev. 

 G. Wheeler criticising Mr. Tutt's statement that as a rule the two species in the 

 lowlands are rarely if nncommon together remarked that at Berisal they often 

 occurred simultaneously in vast numbers, though P. argijrognomon would sometimes 

 be a full month before P. argus came on the scene. Mr. H. St. J. Doiiisthorpe read 

 a paper " On (he Origin and Ancestral Form of Myrmecophilous Coleoptera ;" Mr. 

 W. L. Distant, on "Rhynchota Malayana ;" Mr. J. ¥.. Collin, by Mr. W. Wesche, 

 " On the Antennae of Diptera, and the present classification of the Nemocera, with 

 two subsidiary sections bearing on the latter subject;" Mr. G. A. K. Marshall, 

 "On Reciprocal Mimicry: A Rejoinder to Dr. F. A. Disey." Dr. Dixey had 

 put forward the view that within the limits of a Miillerian association every 

 species exercises a mimetic influence upon every other, the amount of the influence 

 depending upon its dominance, which is determined by its numbers, distastefulness 

 and general notoi'iety. Thus, as between any two species, the mimetic approach 

 would be mutual and result in an interchange of characters. This interchange 

 would be proportionate to the relative dominance of the two species ; where this 

 is unequal, the weaker species would take on, to a considerable extent, the super- 

 ficial appearance of the stronger, while the latter would only adopt some small 

 characters from its mimic ; but where the dominance is equal, the interchange 

 would be equal, so that this would constitute the optimum condition for the pro- 

 duction of Reciprocal Mimicry. Mr. Marshall contended that this gravitational 

 conception of mimicry was really based on a false analogy and was at variance with 

 the real principle of Miiller's theory. While admitting the theoretical possibility 

 of mimetic interchange, he ui'ged that a logical application of Miiller's argument 



