12 Journal New York Entomological Society. [Vol. xm. 



these spiracles I have not been able to observe. That this rudiment 

 of the spiracle is converted into the imaginal disc of the wing seems 

 probable, however, for the following reasons: (i) The disc of the 

 wing always appears in exactly the same area as that in which the 

 spiracle arose and degenerated, ( 2 ) the wing disc frequently shows a 

 concentric arrangement of the cells in early stages but loses this before 

 invagination to form the wing begins, (3) if the wing fundament is 

 not derived from the remains of the spiracle, then, since the wing disc 

 has the exact position occupied by the spiracle, the latter must entirely 

 degenerate and be replaced by new hypodermis, and from this the 

 wing must arise. There is, however, absolutely no ground for belief 

 in such a process and the only conclusion that seems at all tenable is 

 that the wing fundament is derived directly from the remains of the 

 spiracle." Tower states farther that these spiracle discs are quite dis- 

 tinct in the embryo shortly before hatching, but that soon after the 

 larva emerges they either degenerate or subside into a quiescent period 

 so that they are not recognizable from the surrounding hypodermis, 

 but that after this period of rest, the cells begin to grow again and 

 form the wing fundament. 



I shall present what, I think, is conclusive evidence that the wings 

 do not arise from discs of degenerated spiracles, but which points 

 strongly to the supposition that the wings have originated as outpush- 

 ings of the hypodermis at the suture between the pleurum and the ter- 

 gum. 



I have found (1) from the examination of a large number of spe- 

 cies of Coleopterous larva? that the mesothoracic spiracle is present in 

 many species and that in some of these it is functional, while in others 

 the connection with the longitudinal tracheal trunk has more or less 

 completely degenerated but that the spiracle itself is present though con- 

 siderably smaller than the other spiracles and but lightly chitinized. 

 ( 2 ) That in the larvae of some winged insects possessing both meso- and 

 metathoracic spiracles these spiracles have not migrated forward to any 

 appeciable extent, in some cases occupying exactly the same positions in 

 their respective segments that the abdominal spiracles occupy in their 

 segments. (3) That the wing fundament arises distinctly either 

 above or below the positions occupied by the thoracic and abdominal 

 spiracles. That is to say, the positions of the spiracles on the pleurce 

 of their respective segments varies in different insects, being in some 

 cases distinctly below the origin of the wing and in others distinctly 



