SYSTEM OF INSECTS. 391 



this Order have only two wings, yet the under or secon- 

 dary wings of the other Orders have in them their re- 

 presentative 3 . Their poisers also, I formerly observed 

 to you, are probably more connected with their respira- 

 tion than with their flight b . 



DEF. Metamorphosis incomplete, or coarctate. 

 Mouth proboscidate c . 

 Prothorax replaced by a collar. Sutures of the 



trunk mostly spurious d . 

 Wings two, with winglets attached to them : 



neuration various 6 . Poisers. 

 Tarsi pentamerous. 

 Ovipositor various f . 



11. ApHANiPTERA g (Aptera L. Lamarck. *Wiyngota F. 

 Suctoria Latr.) This is an osculant Order, and is dis- 

 tinguished from the other Aptera L. in undergoing a 

 regular metamorphosis. The larva is vermiform, the 

 pupa incomplete, and inclosed in a cocoon. Probably 

 the common flea and the chigoe would form distinct 

 genera. The number of species of fleas is greater than 

 has been supposed. I have been informed that Dr. Leach 

 is acquainted with fourteen British species alone. Be- 

 sides their metamorphosis, they are distinguished from 

 the Aptera by the number of segments into which their 

 body is divided, and by their pentamerous tarsi. Some- 



VOL. II. p. 354. b Ibid. p. 355. 



VOL. III. p. 465. d Ibid. p. 552. 



* Ibid. p. 632. ' See above, p. 163. 



g From uQavw, inconspicuous ; so named because something like 

 elytra appear. 



