m] OLD-WORLD MIMICS 21 



tail, whereas in the Pieridae and Papilionidae meta- 

 morphosis takes place with the chrysalis attached by 

 the tail but supported also by a fine girdle of silk 

 round the middle so that the head is uppermost. The 

 larvae also afford characters by which some of the 

 families may be distinguished — those of the Papilionidae 

 for example having a process on the back which can 

 be extruded or retracted. 



Owing to the great size of the family of the Nym- 

 phalidae, in which the number of species approaches 

 5000, it is convenient to deal with the eight sub-groups 

 into which it has been divided. The characters serving 

 to mark off the sub-groups from one another are various. 

 Sometimes it is the minuter structure of the tarsus, at 

 others the form of the caterpillar or the chrysalis, at 

 others the arrangement of the nervures that form the 

 skeleton of the wing. Into these systematic details, 

 however, we need not enter more fully here 1 . What is 

 important from the standpoint of mimicry is that 

 these divisions, made solely on anatomical structure, 

 correspond closely with the separation of models from 

 mimics. Of the eight sub-families into which the 

 Nymphalidae are divided four, viz. the Danainae, 

 Acraeinae, Heliconinae, and Ithomiinae, provide models 

 and some, but far fewer, mimics ; two, the Satyrinae 

 and Nymphalinae, provide many mimics and but few 

 models, while two groups, the Morphinae and Bras- 

 solinae, practically do not enter into the mimicry story. 



1 The classification adopted is that used by Dr Sharp in the 

 "Cambridge Natural History," Insects, vol. 2, 1901. 



