Wings of the Hemiptera. 97 



order, I incline to the opinion that the structure first described 

 is the peculiar characteristic of the Heteropterous division of the 

 Hemiptera, and that that last described is peculiar to the Homop- 

 terous division of that order. I think I am justified in estimating 

 the former structure as the more perfect, and consequently more 

 difficult to disengage of the two. 1 am perhaps incorrect in the 

 view I now advance of the occasion for a different structure in 

 the two divisions of this order, but the difference which presents 

 itself in the nature of the wings in those two divisions naturally 

 suggests it. May not the more homogeneous texture of the upper 

 and under w ings, and the comparatively firmer and more compact 

 structure of the lower one in the Homoptera, require a less intimate 

 fastening of the two together than in the Heteroplera? in which the 

 wings, from the lower one being comparatively thinner and more 

 membranous in its texture, and its structure being adapted for 

 folding up when at rest, (which necessarily detracts from its com- 

 pactness and firmness when extended,) are probably more exposed 

 to accidental disturbances during flight, and more difficult to re- 

 engage when separated, thus requiring a comparatively more per- 

 fect and inseparable connexion. 



By the detection of the above described apparatus, the true 

 alary nature of the hemelytra in this order is established, which 

 hitherto appears to have been more or less a subject of doubt 

 amongst entomologists. 



The difference between the simple structures I have above 

 described, and the more complex series of booklets which con- 

 nect the wings of the Hijmenoptera, is interesting. 



I apprehend that were the wings of the latter not actually 

 united along the greater part of their lengthy they would not, 

 from their membranous texture, present one firm and air-tight 

 surface to act on the air, which I conjecture to be essential in 

 both these orders. This, in the Hemiptera, is effected by the 

 more firm texture of the upper wing, and the peculiar relative 

 forms of the two wings when vinited. 



I cannot conclude without drawing attention to the circum- 

 stance, that the Hemiptera, in possessing this apparatus, appear 

 to occupy the place of transition (as respects the wings) from the 

 Coleoptera, in which the upper wings are simply organs of pro- 

 tection, to the Hijmenoptera, in which they are purely organs of 

 flight; those of the Hemiptera partaking in about equal degree 

 of both these characters, the texture of the upper wing also being 

 actually divided, so that about a moiety nearly approaches to 

 each of the two orders in question, and the connecting apparatus 



