The origin and development of the wings of Coleoptera. 



527 



Family and Species 



CarahiJœ 



Carabus sp.? 

 Coccinellidae 



Hippodamia ISpunctata 



Coccinella bipundafa 



Epilachia borealis 

 Dermestidae 



Anthrenus verbasci 

 Elateridne 



Melasis pectinicornis 

 Buprestidae 



Buprestis rufipes 



Chrysohothris femorata 

 Scarabaeidae 



Lachnosterna fusca 



Pelidnota punctata 



Osmoderma scabra 

 Cerambycidae 



Orthosoma brunneum 



Phymatodes variabilis 

 Chrysomelidae 



Leptinotarsa decemlineata 

 CurcuUonidae 



Macropus sp.? 



Mononychus vulpeculus 



Why is there this difference in the time when the wings appear 

 and begin to develop? Is it associated with the type of larval en- 

 vironment? or is it associated with primitive or speciahzed conditions? 

 These are questions which, although not directly answerable, can 

 better be discussed after some other evidence bearing upon this sub- 

 ject has been considered. 



2, Formation of Larval Wings. 



After the first pit-like invagination is formed it elongates rapidly, 

 forming a furrow nearly the entire length of the disc. This groove 

 now deepens rapidly (PI. 14, Figs 2 and 7; PL 15, Fig. 17, PL 17, Fig. 27) 

 and simultaneously the dorsal part of the invaginated tissue becomes 

 thickened (PL 17, Fig. 27) until it may be twice as thick as the 

 ventral part. This invagination completed, the wing is now ready to 

 enter upon one of the special lines of development which they follow 

 in reaching the adult stage. 



