EXTERNAL ANATOMY OF INSECTS. 603 



lighten a hard elytrum, these ridges may serve to 

 strengthen a soft one, and it is by these that the first ap- 

 proach is made to the reticular structure of tegmina or 

 the wing-covers of Orthoptera: Lycus palliatus, &e., in 

 its elytra exhibits a direct resemblance of the reticula- 

 tions of nervures. 



8. Clothing. To what I have before said on this 

 subject in general a I shall here add a few remarks, 

 which, though they more properly belong to elytra, may 

 in many cases be extended to the whole body of a beetle. 

 In various instances it happens that the beautiful mark- 

 ings of these organs, as in Macropus longimanus, whose 

 elytra when denuded are black, are produced by short de- 

 cumbent hairs ; in some these variegations are the effect 

 of scales resembling those of Lepidoptera, often of a 

 metallic lustre ; from these scales is derived all the bril- 

 liancy of the diamond-beetle [Entimus imperialism Germ.); 

 in some the scales are so minute as to resemble the 

 pollen of flowers, as the white marks observable on the 

 green elytra of the rose-chafer {Cetonia auratd). 



9. Colour. The organs of flight in the majority of 

 the Orders with respect to colour are usually the most 

 gaily decorated part of insects; I therefore deferred the 

 notice of that subject till I came to treat of them. In 

 general the colour of insects is either inherent in the 

 substance of their crust, or produced by the hairs or scales 

 that either partially or totally cover it. To confine my- 

 self to the Coleoptera, of whose elytra we are treating, it 

 may be observed, I think, in general, that the majority of 

 those that feed upon putrescent substances, the sapro- 

 pkagous tribes of Mr. W. S. MacLeay, are commonly of a 



* See above, p. 399 — . 



