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ME. H. W. BATES ON THE INSECT FAUNA 



is some cause to believe that they are unpalatable to insectivorous 

 animals — at least the Acrceoid group. This would not explain, 

 however, the numerous mutual resemblances of the Heliconince. 

 All that we can say is, that some species are more successful in the 

 battle of Hfe_than others, a^d JthaiT it is an advantage to others 

 noT^therwise provided for if they are brought to be deceptively 

 similar to them. The process by which this is brought about in 

 nature is a problem involved in the wider one of the origin of all 

 species and all adaptations. There are some curious facts, however, 

 in the geographical distribution of the species and varieties of 

 certain members of the genus Leptalis which throw great light 

 on the subject, at least as far as the Leptalides are concerned, 

 which offer perhaps the most remarkable cases of mimicry. It 

 would appear byTmese faets that a mimetic species has not always 

 existed under the same specific mimetic dress which it now wears, 

 as the following example shows. Leptalis Lysinoe in one district 

 is very variable, but none of its varieties mimics very closely a 

 Heliconine species there residing ; they rather tend to imitate 

 species of Stalactis — another flourishing group belonging to a 

 different family ; but a few individuals occur intermediate in cha- 

 racter, and quite uncertain in their analogies. In another district, 

 again, this species is very variable, and some of the varieties are 

 indeterminate in their analogies, but the greater n ji mber resemble 

 to deception one or other of t hree species of Ithomia , amongst 

 which only they are found, and from which they are quite j mdjr 

 stinguishable, except when closely examined in t he hand . In a third 

 locality this Leptalis is found under one form only, distinct from 

 any of the varieties occurring elsewhere, but mimicking closely an 

 Ithomia also found there and not in the other two districts. Thus 

 we see that, although the changes a species undergoes, first simply 

 variable, and then presenting local varieties closely mimicking 

 other forms, cannot be watched in nature as they take place suc- 

 cessively, they can be seen as it were simultaneously by tracing 

 lliom over the area of its distribution. Leptalis Lysinoe is a 

 Species of great rarity, and therefore liable to complete extinction. 

 It seems fair to conclude that, as the Itho mia w lnclijiunimi cs are 

 certainly sp ared by the swarms of insectivorou s birds which dail y 

 sweep thro ugh their abodes, the L epta lis, not being so f avoured, 

 fiwcapeB destruction bv wearing the livery of the IthomtaT. It may 

 he .added that the family to which leptalis belongs (Picridce) arc 

 certainly much persecuted by insectivorous animals. As, then, the 

 Lrjilahn varies from one locality to another, some few of its varia- 



