136 MODERN CLASSIFICATION OF INSECTS. 



the mouth prominent, with strong exserted mandibles (^fig- 10. 7. and 

 10. 2.), entire at the tips*; the thorax orbicular, or nearly semicir- 

 cular, forming a shield to the head; the tarsi are 5-jointed, the fourth 

 joint being but slightly smaller than the preceding {fig. 10. 6.); the 

 labrum transverse and emarginate ; the palpi filiform, the last joint 

 being slender ; the maxillae {fig- 10. 3.) with two lobes, the external 

 one narrowed at the base, and the internal armed with a corneous hook ; 

 the mentum transverse, and the labium large and cordate {fig- 10. 4.) ; 

 the antennae are thickened at the tips {fig. 10. 7. * and 10. 5.). 



These insects are the most pre-eminently Necrophagous f of the 

 stirps, it being their duty to remove from the surface of the earth 

 animal matter in a dead and putrifying state, which would otherwise 

 become injurious to health ; hence they are constantly found in carrion 

 and the carcasses of animals already exposed to the attacks of flies 

 and other insects, whose office it is first to make an inroad upon such 

 substances, which these insects subsequently and more effectually 

 remove. Some species, indeed, frequent trees, where they probably 

 devour Lepidopterous larvae ; others feed upon the inhabitants of 

 small shells found upon the banks of rivers, where they station them- 

 selves to lie in wait also for such dead animals as are thrown ashore. 

 Thus the Rev. F. W. Hope informs me, that the Silpha laevigata feeds 

 voraciously upon live snails, digging its strong jaws into the fleshy 

 bodies of the latter, which in vain endeavour to escape. Its larva 

 also exhibits similar propensities ; and in like manner Linneeus 

 {Lachesis Lapjmn. vol. i. p. 152.) mentions an insect, evidently one of 

 the flat Silphidffi from the figure, which feeds on fish, and is found 

 running about amongst the scales offish, as well as in the crevices of 

 the floors of the Lapland huts, and which smells like rue. The Ne- 

 crophagous species do not, however, strictly confine themselves to dead 

 animal matter, since I have discovered individuals of Necrophoru& 

 vespillo devouring a large decaying fungus in which they had taken 

 up their abode. The fetid odour which these insects possess, as 

 well as a black nauseous fluid which they discharge from the mouth, 

 renders them obnoxious. This, however, is not emitted by speci- 



* In Silpha 4-punctata one of the mandibles is entire, and the other bifid at the 

 tip {fig. 10. 2. and 2*.). 



+ Mr. Kirby has separated the genus Necrophorus from the Necrophaga, and 

 raised it to a section, Entaphia, of equivalent value with the Adephaga, Brache- 

 lytra, &c., a step of which the adoption does not appear to me to be advisable. 



