. Coleoptera. Beetles. BEETLES. 391. Flo. -JCti. — Hjiilrojivru (iriscoatriatua. clttutus is the largest species from tlie I'uited States, where it is common in the Atlantic region. It is al)out s. The larv;i3 of Gyi'inid;c resjiire I>y means of ciliate gills and a closed tracheal system. These gills are situated one on each side of every alidominal segment, ami an additional pair upon each side of the anus, — in all, ten ])airs of gills. These ciliate branchiai serve as swimming organs, enabling the larvie to swim rajiidly. Notwith- standing their active aquatic lifi' these larvie are subj
. Coleoptera. Beetles. BEETLES. 391. Flo. -JCti. — Hjiilrojivru (iriscoatriatua. clttutus is the largest species from tlie I'uited States, where it is common in the Atlantic region. It is al)out s. The larv;i3 of Gyi'inid;c resjiire I>y means of ciliate gills and a closed tracheal system. These gills are situated one on each side of every alidominal segment, ami an additional pair upon each side of the anus, — in all, ten ])airs of gills. These ciliate branchiai serve as swimming organs, enabling the larvie to swim rajiidly. Notwith- standing their active aquatic lifi' these larvie are subject to parasitism by three or four species of Hymenoptera. The flattened water-fieetles beloiiiece, and is prolonged in a triangular process pos- teriorly, their abdomen has six segments. The legs of tliese beetles, especialh' the postei'ior pair, are oar-shaped and clothed with long hair, being consecjuently well fitted for natation; but these insects are not contined to swimming as a mode of locomotion, for they are pro\ idecl with serviceable wings, and during the night fly from pond to pon<l. These beetles ai'e apparently guided to water by sight, for they often fly against green-luuises, the glass of which they mis- take for the surface of water. Many Dytiscida; emit between the head and prothorax, a milky secretion, arid between the mesothorax and metathorax a yellowish fluid; the function of both these odorless fluids is not determined with cer- tainty. At each side of the anal end of the intestine are two glands which furnish a strong odorous, acid fluid, said to contain butyric acid ; these anal glands, which are not rare in adephagous Coleoptera, are defi'usive in function. 3Iany species of Dytiscidie stridulate ; thai is, produce more or less musical siiunds, both ;i{\ action of tlie ]iosteri elytra. The anterior and often the middle tarsi of nniles, in certain genera of this famih', have :i jiart of their joints widened, and provided with ]ieduiic
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Keywords: ., boo, bookcollectionbiodiversity, booksubjectbeetles, bookyear1884
