293 



NOTES AND COMMENTS. 



DIAPOSEMATISM, OR RECIPROCAL MIMICRY. 



In addition to the usual well-illustrated papers dealing with 

 exotic butterflies, etc., the ' Transactions of the Entomological 

 Society of London ' for 1908 (part I.) contain a paper on 

 ' Diaposematism, with reference to some limitations of the 

 Miillerian Hypothesis of ^Mimicr}^' by Mr. Guy A. K. Marshall. 

 In this the author points out that ' one of the most striking 

 features in connection with the philosophical study of the 

 phenomena of mimicry among butterflies in recent j^ears has 

 been the marked tendency to la}' an ever increasing emphasis 

 upon the importance of the selective factors suggested by 

 Fritz Miiller, and to minimise the influence of what is known 

 as Batesian mimicry. It has even been suggested that every 

 known case of mimicry among butterflies can be more satis- 

 factorily interpreted as being due to the operation of Miiller's 

 principle.' 



TWO THEORIES OF MIMICRY. 



' The essential difference between these two theories 

 of mimicry lies in the fact that one explains how an edible (or 

 less unpalatable) species will derive advantage through assum- 

 ing a superficial likeness to another which possesses nauseous 

 (or more unpalatable) qualities (Batesian mimicry) ; whereas 

 the other shows how one nauseous species will benefit by 

 mimicking another having the same qualities (Miillerian 

 mimicry). Now although there can be little doubt that a 

 good many cases of mimicry originally adduced in support of 

 Bates' theory, must now be explained on Miillerian lines, yet 

 the universal application of this latter principle to butterflies, 

 involving as it does, the assumption of unpalatability in every 

 mimic, seems open to some serious objections.' These objec- 

 tions are given in detail in this suggestive paper. 



THE BEARDED TIT. 



]\Ir. W. p. Pycraft has recently recorded* some interesting 

 facts in connection with the nest and nestlings of the Bearded 

 Tit. During the Whitsuntide holidays he found a nest of this 

 species on the ground, almost five or six yards from the water. 

 It contained six young, all more or less mangled, evidently the 

 work of a mole — the runs of which occurred beneath the nest. 



go'i August I. 



* British Birds, July 1908. 



U 



