OF THE- ORDER COLEOPTERA. 259 



form a sort of ginglymous articulation with the base of the 

 anterior coxae. The other impressed puncta so often to be 

 seen on the different parts of various insects, which, some- 

 times, so entirely cover the surface, that scarcely any interval 

 is discoverable between them, though in many cases they 

 appear to be mere impressions which attenuate, but do not 

 perforate the crust, yet in others, perhaps, equally or 

 more numerous, they are real jjores which pass through the 

 integument. If, for instance, you take the thoracic shield 

 of the cock-chafer {Melolontha vulgaris), and after removing 

 the muscle, &c., hold it against the light with the inner side 

 towards the eye, you will see the light through every punc- 

 ture ; or take the elytra of Geoirupes stercorarhts, or any 

 common beetle in which these organs have punctate striae, 

 and examine them under a lens on the inside, and you will 

 distinctly see that the punctures pass through the elytrum, 

 and the membrane that lines it. It is not improbable that 

 in the case last mentioned these pores may be of use, as the 

 spiracles are usually closely covered by the elytra for the 

 better transmission of air to those respiratory organs." 



The colour of elytra varies considerably. A curious ob- 

 servation is»made on this subject by Mr. Kirby that the 

 majority of the coleoptera which feed upon putrescent matter 

 are darker and more dismal in their appearance than those 

 which feed on living prey, or fresh substances. Many 

 families or tribes are distinguished by the peculiar colours 

 of their elytra, which, as a secondary character, is useful in 

 classification. 



Before dismissing this part of our subject it may be 

 requisite to say a word or two on the uses to which the 

 elytra are destined to serve. Their most evident use is to 

 protect the wings from injuries, to which they might other- 

 wise be liable, in the haunts which many of those animals 



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