ORGANS FOUND ON THE HALTERES AND WINGS OF INSECTS. 143 



In Imcanus Cerviis, Melolontha vulgaris, and Cetonia aurata they are not so large, Ijut 

 still are numerous. 



In Carahus granulatus they are found in the rudimentary second wing, more difPused 

 over it than in some other genera, inasmuch as other nervm-es than the suhcostal are 

 furnished with them, though not to the same extent. 



In an apterous Beetle which I examined, I did not find any similar organs on the part 

 of the side corresponding to the position of the wings. 



With regard to the distribution of the nerve in the elytron of the Coleoptera, there are 

 some curious facts, which, I think, have not been hitherto noticed. If the elytron he 

 treated in the way above mentioned, and first bleached if it be dark-coloured, the 

 branching trachete will at once be recognized, accompanied by the nerve, which gives 

 out branches as it proceeds. Now, m all the elytra of beetles I have examined, there is a 

 number of distinct projections Irom the whole dorsal surface, in many hemispherical, in 

 some like small papillae just raised above the cuticular surface; these eminences are 

 arranged in a tolerably regidar manner, and are quite distinct from other irregularities of 

 sm-face. The hemispherical forms are very transparent, the wall of the elytron being 

 deficient beneath them, as in those before described. There are two or three papUlse at 

 the highest point of the vesicle. Some, when viewed by polarized light, exhibit a dark 

 cross, something after the manner of starch-cells ; those of Melolontha show it well. 



In many beetles the vesicle or papilla is accompanied by a hair, which always, I 

 believe, when so situated, overarches it, as if for the purpose of affording protection. 



Now, into each of these vesicles and papillae a branch of the nerve can be distinctly 

 traced, as I have shown in the two drawings taken from Melolontha (Tab. XXVII. fig. 2) 

 and Carahus (Tab. XXVIII. fig. 1). In the case of Melolontha the hair may be seen 

 overarching the vesicle. 



"With regard to the Lepidoptera I have found nothing new, except that the organs 

 are well developed in the female Vapourer Moth {Orgyia) on the rudimentary wing. 



In none of the Orthopterous specimens hitherto examined have I been able to find 

 any structure like that described in the other gi-oups. A nerve, small in some, but large 

 in Mantis religiosa, is to be found entering the wings, yet I have been tmable to make 

 out anything satisfactory, except a few scattered vesicles on one or two of the nervures. 



In the Neuroptera these organs can be distinctly found, though not quite so fuUy 

 developed as in most of the preceding groups. In lAhellula depressa they are not, rela- 

 tively to the size of the insect, by any means so numerous as in the Coleoptera. I have 

 drawn those of Agrlon, where they are but few ; and those of Fhrt/ganea, which are rather 

 more simple. In the Flea {Pulex irritans), I have been unable to detect anything 

 connected with this subject. 



I have not been able to distinguish any difference between the sexes in reference to 

 these structures, their relative size corresponding to that of the individual, which is 

 generally larger in the female. The species of a given genus, especially of the Dipterous 

 group, exhibit a marked similarity in the appearance of these organs ; so that it is possible, 

 by examining them, to tell to what genus any Fly, whose halteres are presented to you, 

 belongs. 



