100 



Hemiptera), he observes : " My British specimens have 

 but short, rudimentalj oval hemelytra, like those of the 

 bed-bug ; but I possess one of Bosc's original examples, 

 described by Fabricius, not quite so large as the others, 

 in which the wings are fully developed. I do not, how- 

 ever, on that account, regard the former either as pupse 

 or distract species, but as undeveloped specimens iu the 

 imago state*." And whilst discussing the Hydro- 

 metridce, he expresses himself thus : " It appears to me, 

 that, from causes of which vre are ignorant, numerous 

 individuals of many of the species of these tribes are 

 subjected to an inferior kind of development iu the 

 imago state, which does not allow the acquirement 

 of wings, — which, however, in certain cases, acquire 

 their full size. Hence, I consider that the apterous 

 specimens of Hydrometra stagnorum, those with very 

 short elytra, and those with the full-sized wings and 

 wing-covers, are all in the imago state, although some 

 are more perfect than others t-" And, again, in his 

 reflections on the Hemiptera, Mr. Westwood says (and 

 most entomologists are aware of the fact) : " The species 

 of Gerris, Hydrometra, and Velia are mostly found per- 

 fectly apterous, though occasionally with full-sized wings. 

 Chorosoma miriforme, Prostemma guttula, Pachymerus 

 brevipennis, &c., are generally found with very short 

 wing-covers, but sometimes vrith full- sized wings J." 

 In like manner, the Cimex apterus, Linn, (one of the 



* Introduction to the Modern Classification of Insects, ii. p. 466. 

 t Id. ii. p. 469. + Id. ii. p. 454. 



