618 EXTERNAL ANATOMY OF INSECTS. 



where they are met by a traversing nervure ; the object 

 of this is doubtless to strengthen the membrane. 



7. Both tegmina and hemelytra are most commonly 

 naked, yet very short hairs are found on those of some 

 species of Cercopis, and in many more instances in those 

 of the latter description, as in Notonecta, several Lygai 

 and Reduvii, &c. 



8. Colours in hemelytra are very various, and in many 

 instances are peculiar to families ; in certain Lygcei (L. 

 Hyoscyami, &c.) black and red; in Lygceus compressipes 

 and affinities a dingy black ; in some Reduvii black with 

 a large white spot ; — but it is needless to enlarge further 

 on this subject. 



9. That hemelytra are used in flight is evident not only 

 from the large space allowed for their muscles % but like- 

 wise from a circumstance noticed by M. Chabrier, that 

 in flight, in the Pentatomce Latr., the corium of the he- 

 melytrum is fixed to the wing a ; in which case both must 

 describe the same arc. 



iv. Wings. We are next to consider organs which are 

 exclusively appropriated to Jlight, and therefore are pro- 

 perly denominated wings. These in the Orders that have 

 elytra, tegmina, or hemelytra, are the pair that correspond 

 with the secondary wings of the other Orders. It may 

 be said, indeed, that in several instances both tegmina and 

 hemelytra do not differ at all in substance or use from the 

 wings that they cover. This is true ; but as their struc- 

 ture in other respects is the same with that of those that 

 are more solid and less apt for flight, it was convenient to 

 consider them under the same name. 



1 Chabrier Analyse, &c. 23. 



