101 



Lygmda:) " exhibits^ in an eminent degree, the ordinary 

 occurrence of an imperfect perfect-state; whilst indi- 

 viduals are occasionally found with fully developed organs 

 of flight*". LycBUS brevipennis, Lat., also ordLuarUy 

 occurs ■with abbreviated hemelytra; but it has been 

 found with them perfect by Westwood, as well as with 

 metathoracic wings. 



None of the above examples however would appear to 

 do more than refer to the alary iastability of the Insecta, 

 as a matter of fact ; but this is all for which we are now 

 contendiagj — the preceding chapter having been in part 

 devoted to some of the presumptive causes of it. Whether 

 the specimens of Oncocephalus griseus, to which Spiuola 

 called attention, were insular ones, I cannot say ; but he 

 seems to have noted an example in which an opposite 

 phsenomenon to those which Mr. Westwood has cited, 

 was displayed, and moreover to have speculated on the 

 conditions produciug it, when he suggests : " L'iafluence 

 du climat septentrional parait avoir arrete le developpe- 

 ment des organes du volf." And, agaiu, when com- 

 menting upon the other tendency in a representative of 

 the ReduviadcB, he says {' Essai,' p. 96) : " Je pense que 

 la presence des ailes et leur developpement dependent 

 du climat." Whilst treating of two British species of 

 the same family, Mr. Westwood observes : " The Pro- 

 stemma guttula, Fab., and Coranus subapterus, Curt., are 

 interestiag on account of their being generally found in 



* Introduction to the Modem Classification of Insects, ii. p. 480. 

 t Essai, p. 103. 



