. Entomology : with special reference to its biological and economic aspects. size.—? After Woodward. development in number and variety; in fact, the Ephemeridse,like the BlattidcT. achieved their maximum development agesago, when they attained an importance strongly contrastingwith their present meager representation. The Permian has supplied a remarkable genus Engercon(Fig. 299) with hemipterous mouth parts associated with fili-form antennse and orthopteroid wings. The earliest unques-tionable traces of insects with an indirect metamorphosis arefound in the Permian of Bohemia, in the shape o
. Entomology : with special reference to its biological and economic aspects. size.—? After Woodward. development in number and variety; in fact, the Ephemeridse,like the BlattidcT. achieved their maximum development agesago, when they attained an importance strongly contrastingwith their present meager representation. The Permian has supplied a remarkable genus Engercon(Fig. 299) with hemipterous mouth parts associated with fili-form antennse and orthopteroid wings. The earliest unques-tionable traces of insects with an indirect metamorphosis arefound in the Permian of Bohemia, in the shape of caddis wormcases. Triassic,—Triassic cockroaches present interesting stagesin the evolution of their familv. Through these ]\Iesozoic DISTRIBUTION 389 species, the continuity between Palaeozoic and recent cock-roaches is clearly established—which can be said, of no otherinsects; and in fact of no other animals, the only comparablecases being those of the horse and the molluscan genus Planor-bis. In the Triassic period occur the first fossils that can be Fig. Eitgereon bockingi. Three quarters natural size.—After Dohrn. referred indisputably to Coleoptera and Hymenoptera, the lat-ter order being represented first, as it happens, by some ofits most specialized members, namely ants. Jurassic.—At length, in the Jurassic, all the large ordersexcept Lepidoptera occur; Diptera appear for the first time,and Odonata are represented by many well-preserved speci-mens, while the Liassic Coleoptera studied by Heer numberover one hundred species. The Cretaceous has yielded butfew insects, as might be expected. Tertiary.—In the rich Tertiary deposits all orders of insectsoccur. Baltic amber has yielded Collembola, some remarkablePsocidce, many Diptera, and ants in abundance. Of 844 spe- 390 ENTOMOLOGY cies taken from the noted Miocene beds of CEning-en, nearlyone half were Coleoptera, followed by neuropteroid forms(seventeen per cent.) and Hymenoptera (fourteen per cent.)
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