EXTERNAL ANATOMY OF INSECTS. 593 



are represented by the four wings a : this opinion, how- 

 ever, is not yet fully proved ; a remark which may also be 

 applied to a more recent one of a celebrated French 

 writer, who seems to think their origin and structure 

 aerostatic, that they are auxiliary to the legs, and bor- 

 rowed in part from the respiratory organs b . Were I 

 disposed to enter into these subtile speculations, I might 

 here recall your attention to the analogy that, in their 

 metamorphoses, exists between the Saurian Reptiles or 

 lizard tribe and insects, and conjecture that the wings of 

 the Draco are really representatives of the mid-legs of 

 Hexapods, thus preparing to disappear altogether ; but 

 I shall content myself with throwing out this hint, which 

 you are welcome to pursue. The organs of flight in 

 general may be considered as to their number, kinds, and 

 composition. 



i. Number. The most natural number is four, for this 

 obtains in the majority. In almost every Order, indeed, 

 there occur instances of insects that have solely a single 

 pair or none c . 



a MacLeay, Hor. Entomolog. 413 — . Mr. MacLeay's opinion seems 

 to receive some confirmation from a circumstance overlooked when 

 the larvce of insects were treated of above (p. 130 — ), and to which 

 he alludes (411); namely, that in that state they consist of two seg- 

 ments more than in the imago; these follow the three pedigerous 

 segments, have no pro-legs, and are supposed to belong to the trunk 

 rather than to the abdomen. To make this circumstance bear upon 

 the question, it must be proved that in the perfect insect these seg- 

 ments in some manner become the back of the trunk and bear the 

 wings. This would not be more wonderful than many changes that 

 are known to occur in insects, 



b Latreille, Organization exterienre des Ins. 173—. s 



c For instance Meloe, the female glow-worm, Lygcsus brevipennis, 

 Ephemera diptera, Cynips aptera, neuter ants, &c. &c. 



VOL. III. 2 Q 



