350 THE PLACE OF MIMICRY 



Thus, too, traces of the scalloped border are almost 

 invariably retained by the mimetic species of Hypolimnas, 

 and a Heliconine can nearly always be distinguished at 

 a glance by the short radiate white lines on the black 

 border of the hind wing under side. These take the 

 place of roundish white spots which occupy the same 

 position in the Ithomiine model. 



It is possible that simple and easy means of discrimina- 

 tion such as those described in the last paragraph may 

 facilitate recognition between the sexes (see p. 358). But 

 whatever be the value to the species, their persistence is 

 a far greater difficulty on the Batesian than on the 

 Mtillerian Hypothesis. 



13. Classes of Facts which have Recently been Urged in 



Support of the Batesian Hypothesis. — Many arguments 



have been given in favour of the Miillerian as opposed 



to the Batesian interpretation of Mimicry, and now two 



counterbalancing considerations remain to be discussed. 



a. Butterflies Exhibiting Mimetic Resemblance 011 the 



Upper Surface of the Wings and Procryptic Defence 



on the Under Surface. 



Instances of this interesting combination of methods 



are rather rare, the chief examples being found in a single 



Sub-Family in the Old World and a single genus in the 



New. Other instances belonging to the Nymphalinae are 



however, not uncommon. Dr. Dixey considers that the 



same combination is to be found in several Pieriuae, e. g. 



in the genera Teracolus and Eronia} 



In the tropical American Nymphaline genus Protogonius 

 the whole of the species or sub-species are imperfect but 

 undoubted members (as regards the upper surface) of the 

 principal Ithomiine-centred Synaposematic combinations 

 of their respective localities. They reproduce roughly 

 but clearly the characteristic elements of the pattern 

 whatever they may be : the barred black and tawny 

 pattern of Central America and Venezuela, the over- 

 spreading yellow of Trinidad, the darkened hind wing 

 of the Guianas, the yellow hind wing stripe and white fore 



1 For Mimicry in the latter genus see Proc. Ent. Soc, Lond., 1906, 

 pp. xxx, xxxi. 





