suggestions as to insect colours and iKittern^. 573 



he knows in the living state, and of the skunk, he cannot 

 contend,! think, that his criticisms are powerful enough to 

 transfer these examples into the bionomic group which con- 

 tains the well-known examples of cryptic colouring — the 

 skunk into the same category as the hare or ptarmigan, the 

 under-side colouring of the Danaine butterflies, or the Nym- 

 phaline genus LimeniUs (BasilarcJiia) into the saraecategory 

 with that of Grapta or Kallimoj, etc. I believe the whole 

 of his criticism of warning colours can be accepted, and 

 can be reconciled with the existing hypotheses. All 

 animals Avith warning colours have enemies, all are 

 liable to special attacks, in times of exceptional hunger, 

 by enemies which would at other times neglect them. 

 Even the skunk has special bird enemies. Provided such 

 forms are easily seen and avoided by enemies which 

 respect their special modes of defence, it is clearly an 

 advantage to be as far as possible concealed from those 

 which do not respect them. Hence conspicuousness, but, 

 as Mr. Thayer tells us, something very far short of ideal 

 conspicuousness. The black and white pattern of the 

 skunk is probably glaring and conspicuous enough to all 

 enemies near at hand, but at the immense distance covered 

 by the long-range sight of a predaceous bird it may melt 

 into an inconspicuous grey. 



The same kind of interpretation probably holds for a 

 cryptic element whenever it exists in the appearance of 

 butterflies belonging to distasteful sub-families. It is the 

 probable meaning of the transparency so widespread in 

 the Ithoniiinm, although I do not think it is so effective 

 in concealing as Mr, Thayer supposes. We must remember 

 that many of these transparent species are excessiv^ely 

 •abundant, flying in clouds often made up of the individuals 

 of several species and different genera. I quite recognize 

 that the transparency may protect such forms against 

 distant enemies, but I should be much surprised if the 

 species of Methona and Tliyridia, as well as Dismorphia 

 orisc, of which they are the models, are not rendered 

 extremely conspicuous to enemies close at hand, by their 

 numbers, habits of flight, and attitudes of rest. As Mr. 

 Thayer has said, the black and white markings will melt 

 into an elusive grey on a rapidly vibrating wing ; but the 

 specially protected groups have developed a sailing flight 

 which shows off the elements of pattern to perfection. 

 When the body in such groups is effacively graded the 



