( xliv ) 



occupied drier ground close by. At Guethary S. arethusa was 

 abundant on the higher open ground. The Lac de la ISTegresse 

 is well sheltered from the sea by an intervening hill. 



I do not know, but the European distribution of morpheus 

 and cedipus suggests them as frequent associates, whilst dryas 

 is probably always common enough to join the group. If not 

 so rare in the S.E. of France as they are [cedijnis is, I believ^e, 

 absent), it is certainly not so widely distributed there as 

 elsewhere. Without forming any theory as to tlie cause of 

 the homceochromatic separation of these butterflies from the 

 other species of the district, it seems difficult to believe tliat 

 it is merely fortuitous. Assuming for the sake of ai'gument 

 that it is an instance of Mlillerian association, several points 

 may be worth noting. The three Imtterflies are of very much 

 the same colour on the wing, and no other of the butterflies 

 flying in the country around at the same time are at all like 

 them. They keep together, and ai-e not mixed up with their 

 neighbours. They fly in a slow, floppy manner, and are 

 captured with the greatest ease. Not to be misunderstood, 

 I must add that even C. cedipus can mend its pace at need, 

 whilst H. morpheus has the capacity for a sudden and almost 

 mysterious disappearance that many skij^pers possess, and 

 *S'. dryas is, when it likes, a very strong flier. 



To associate the three forms together, as differing from 

 everything else, must be as inevitable to the bird or other 

 predaceous enemy, as to the entomologist. Equally, however, 

 it must happen that such enemy, if it were useful to him to 

 do so, could not possibly fail to discriminate between them 

 with the greatest facility. S. dryas is at once separated by 

 its great size, whilst the peculiar hopping, dancing flight of 

 H. morp)heus, in which it shows the colour and even marking 

 of its under-side, is unmistakable. We have here none of the 

 detailed agreement of colour and markings that we are now 

 so familiar with in neotropical groups. 



I do not know of any association of European butterflies 

 that is quite parallel to this one, nor has it before occurred to 

 me to regard any other association of butterflies I have seen, 

 as being of homceochromatic significance, whatever that may 

 be. " Blues " often swarm together, but they seem to be blue 



