THE YOUNG NATURALIST. 



291 



/ Internal nervure 

 g Rudiment of the discoidal nervure 

 gi Upper disco-cellular nervule 

 g2 Middle disco-cellular nervule 

 g3 Lower disco-cellular nervule 

 h Interno-median nervule. 



Figure ii. and iv. pi. 23, vi. and viii. pi. 25, 

 represent the hind wings of the same species. 



The additional references are as follows :— 

 a Precostal nervure 

 c Discoidal nervure 

 gi, g2 Upper and lower disco-cellular 

 nervules 



The others are as in the fore wings. 

 We would call attention to the fact that 

 when they spring from the base of the wing 

 they are called nervures, when they spring 

 from nervures they are called nervules. 



Perhaps the more minute explanations, 

 given in the work we quote from, may be 

 little use to many of our readers, but they 

 may be useful to some of them in time to 

 come, when perhaps our authority cannot 

 be consulted. We therefore proceed to 

 point out the differences and peculiarities in 

 the wings, taking the information from the 

 work in question, but using own own words. 



Taking the forewing of Papilio Homerus, 

 Fig, 1., as our standard, and remembering 

 that the same letters and figures have the 

 same significance in all, it will be seen that 

 in the forewing of Gonopteryx Leachiana, Fig. 

 iii, there are only four nervules (bi, 2, 3 

 and 4) to the Sub-costal nervure, instead of 

 five as in P. Homerus. The upper Disco- 

 cellular nervule is wanting, and therefore 

 the first Discoidal nervule is united to the 

 Sub-costal nervure. The Internal nervure 

 is very slender, and runs to the Sub-median 

 instead of to the inner margin. There is 

 no Interno-median nervule. 

 % In the forewing of Morpho Perseus, Fig. 5, 

 though all the nervures and nervules are 

 the same as in Fig. 1., some of them are in 

 very different positions, especially the Disco- 

 cellular nervules. 



In the forewing of Mechanitis Lysidice, 

 Fig.vii., the greatest difference is the presence 

 of a rudiment of Discoidal nervure, (g), which 

 is entirely wanting in all the others; the 

 lower Disco-cellular nervule is also bent at 

 an acute angle. 



In the hind wings there are two a's, the 

 second one marking the Pre-costal nervure. 

 In Fig. 1., this Pre-costal nervure is bifid, 

 its lower branch- being united at its ter- 

 mination to the costal nervure. Our 

 authority observes " It is this nervure which 

 in a great proportion of the Heterocerous 

 Lepidoptera, projects beyond the margin of 

 the wing, in the form of a single stout bristle 

 in the males, of several weaker ones in the 

 females, which are received into a more 

 or less distinct one on the underside of the 

 anterior wing. This structure never exists 

 in the Diurnal or Rhopalocerous Lepidop- 

 tera, although, for nearly seventy years, 

 most British writers on the Lepidoptera 

 have persisted in stating its existence in the 

 male of Apatura Iris.' 1 The discoidal ner- 

 vure (c) is always simple in the hind wings, 

 there can therefore never be more than two 

 Disco-cellular nervules. (gi.,g2.,) one or both 

 are frequently wanting, see Fig. vi. 



In Fig iv. the Precostal nervure is simple. 



In Fig, vi. the Precostal nervure is also 

 simple. The Discoidal nervure is united to 

 the second Subcostal nervule, and appears 

 to be a third Sub-costal nervule. There is 

 therefore no upper Disco-cellular nervule. 

 The lower Disco-cellular is also wanting, 

 and the cell is consequently open. 



In Fig. viii., the Precostal nervure is also 

 simple. The Costal and Sub-costal ner- 

 vures are united for about half their length, 

 a structure that only occurs in the female. 

 The upper Disco-cellular nervule is bent 

 at an acute angle, and the lower one so 

 placed as to cause the Discoidal nervure to 

 appear to be a fourth Median nervule. In 

 this figure, as in the forewing, Fig. vii., we 

 find the rudiments of a Discoidal nervure, (g). 



