Mr. Edward Doubleday's Remarks on the Genus Argynnis. 479 



M. Lefebvre has pointed out that the nervules may be divided into superior 

 and inferior, according to their position above or below a fold generally visible 

 in the wings of Lepidoptera, to which he gives the name of ^//' cellulaire. To 

 the nervules he proposes to give the names of first inferior, first superior, &c., 

 choosing this fold as his starting-point for numbering them. 



In the Diurnal Lepidoptera he gives the names of costal and subcostal ner- 

 vures to the upper ones ; of median, submedian and internal to the lower ones. 

 The costal nervure admits of no doubt as to its limits, but it has been often a 

 matter of doubt to what nervure his first and second superior nervule ought 

 to be referred, as sometimes they seem to belong to the subcostal, sometimes 

 to the median. This point M. Lefebvre decides by giving them to the sub- 

 costal, because he considers them to be always above the cellular fold. He 

 views the subcostal as generally emitting four nervules, of which either the 

 second or third is often, if not always, branched. 



In the Heterocera he finds " quelques nervules qui n'ont pu etre consignees." 

 These chiefly depend on a central nervure, which he calls the discoidal, which 

 is sometimes above, sometimes below, the cellular fold. 



Such is M. Lefebvre's theory of the wing. After a long examination of 

 the wings of Lepidoptera, from Papilio to the last of the Tineidce, I have 

 arrived at a somewhat different conclusion, in which I have been confirmed 

 by a hasty glance over other orders. I should not speak so confidently 

 of the result of my labours, had I not submitted my observations to my 

 friend Mr, Newport, who entirely coincided with my conclusions ; and thus, 

 having the sanction of our best physiological and anatomical entomologist, 

 I cannot be accused of presumption in differing from all those who have 

 preceded me. 



The theory which I would propound is this : that the normal structure of 

 the wings in Insects is, to have two distinct sets of air-vessels or nervures, 

 three belonging to the anterior half of the wing, three to the posterior; that 

 in those species in which the wings are in the most truly normal condition 

 these nervures are all fully developed, and all subserve to their true functions ; 

 that in descending from these we first find some of the nervures less developed, 

 but still subserving to their functions, then becoming gradually atrophied, and 

 at last disappearing altogether ; and that this gradation depends partly on the 



VOL. XIX. 3 R 



