( viii ) 



once realised that the Ithomiine Eutresis imitatrix, Staud., is an 

 exceedingly good secondary mimic of Ituna itself, the historic 

 mimic of Thyridia (and Methona) upon which Fritz Miiller 

 based his theory. Reference to the Linuiean Society plate 

 published in 1898 showed that nearly all the points of 

 secondary resemblance are clearly displayed, although they 

 had never been recognised. It was almost humiliating to 

 realise the dependence of observation on hypothesis. 



After recognising this interesting example of secondary 

 mimicry in Mr. Kaye's collection, the fine series in the British 

 Museum, including, in these grovips, the Godman-Salvin 

 material, was carefully studied with Mr. G. A. K. Marshall's 

 kind assistance. In the course of the examination certain 

 features of the primary Ithomiine models, Methona confusa 

 and Thyridia psidii, were compared and the conclusion reached 

 that, as regards these points, the Methona has acted as model 

 and the Thyridia as mimic. The Avhole of the conclusions 

 arrived at are embodied in the following account. 



The general appearance of Eutresis imitatrix is far more 

 that of Ituna phenarete, D. & H., than of /. ilione, Cram. 

 The latter is a smaller, more intensely and heavily black- 

 marked, yellower and less transparent insect than phenarete 

 and its Ithomiine mimic. 



The black-shafted, yellow- or orange-clubbed antennae form 

 one of the most conspicuous features of the Methona-Thyridia- 

 centred combination, and one in which mimetic resemblance 

 is very obvious. It is therefore of great interest to compare 

 the colouring of the antennse in species of Ituna and Eutresis 

 with each other and with the Methona and Thyridia. 



Itmia lamiras, Latr. The antennse are yellow, darkened at 

 the extreme base. This darkening extends throughout the 

 basal half in a male specimen from the interior of Colombia, 

 and still farther in a male from the Rio Napo. These are the 

 only exceptions in the series of 41 specimens of /. lamirus 

 in the British Museum. 



Ituna ilione. The antennse resemble those of the primary 

 Ithomiine models : Methona confusa and Thyridia psidii, 

 being intensely black with an orange club. 



Ituna phenarete. The club of the antenna is much longer 



