PROTECTIVE COLOURING AND MIMICRY. 385 



The axiom that the mimicking insect should be rarer than its 

 model is not always carried out, e.g. the Euterpe tereas (Pierinae), 

 which copies the Papilio nephalion. It is often common while the 

 latter is rare. The Colcenis Julia (Nymphalinae) is far com- 

 moner than the deceptively similar but smaller Eueides aliphera 

 (Heliconinae). * 



I must next refer to the sub-families Danainae and Heliconinae, 

 in which mimicry among various genera is the more remarkable, as 

 it is not, apparently, necessary for protective purposes. Dr. Fritz 

 Miiller remarks f that "the Ithomiae of the Amazons and their 

 allies, e.g. Mechanitis, as Bates observes, are imitated by so many 

 butterflies belonging to the most different families, that they may 

 certainly be correctly regarded as quite safe from the pursuit of 

 birds on account of their distastefulness. . . . Among the numer- 

 ous mimics are swarms of Acrcea thalia. The strong-smelling 

 Eueides Isabella and Helicontus eucrate have either individually or 

 together acquired a resemblance to Mechanitis lysimnia, which 

 insect to us is inodorous ; and amongst the numerous butterflies 

 which sufficiently resemble the three above-named species as to be 

 occasionally mistaken for them are species belonging to the 

 Ithomia group (Melinaa), and to the true Danai'des (Lycorea). 

 Thyridia and Ituna (Danaidae) both belong to the class of cases in 

 which the two species which resemble one another appear to be 

 equally well protected by distastefulness. The former belongs to 

 the Ithomia group, the distastefulness of which has been referred 

 to ; and the latter to the Danai'des, which play the same part as 

 models of imitating species in the Old World as the Ithomiae in 

 the New. They appear even after death to defy the ravages of time 

 and the attacks of mites, etc., by virtue of their distastefulness." 



Mr. Bates, in discussing this paper, said, " The numerous cases 

 where species which are themselves apparently protected by their 

 offensive secretions, evidently mimic other species similarly pro- 

 tected, still form a great stumbling-block ; the excessive complexity 



stinging ants being closely copied in form and movement by spiders, He- 

 miptera and Coleoptera. I have an example in the genus Mutilla, which is 

 exactly imitated by the beetle Cyphus Linncei, Sch. 



* "Proc. Ent. Soc.," 1879, p. xx., ete. 



f Ibid. , p. xxv., et scq. 



2 C 



