. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. 288 ZOO-GEOGRAPHICAL DISTRIBUTION [CH. small remnant composed of Holarctic genera and their derivatives. The Tertiary fossil-beds of this region prove, however, that the Megapodagrioninae existed fairly abundantly in Miocene times. We can only conclude that this group was unable to resist a subsequent lowering of the temperature over those areas in which it existed, and so became extinct within the Fig. 151. Fore-wing (30 mm.) of Hetaerina americava Fabr., $, Mexico. Original. The Palaearctic Region. This enormous
. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. 288 ZOO-GEOGRAPHICAL DISTRIBUTION [CH. small remnant composed of Holarctic genera and their derivatives. The Tertiary fossil-beds of this region prove, however, that the Megapodagrioninae existed fairly abundantly in Miocene times. We can only conclude that this group was unable to resist a subsequent lowering of the temperature over those areas in which it existed, and so became extinct within the Fig. 151. Fore-wing (30 mm.) of Hetaerina americava Fabr., $, Mexico. Original. The Palaearctic Region. This enormous region includes the whole of Europe, together with the temperate parts of Africa (north of the Tropic of Cancer) and of Asia and the Japanese Archipelago. The boundary is usually drawn along the western watershed of the Indus, thence along the Himalayas into Thibet and China, north of the Yang- tse-kiang watershed. Although the region is of such great extent, it is by far the poorest in Odonata in the whole world. Japan is the only part of it that contains at all an abundant or striking Dragonfly fauna. Out of 59 genera known to occur, only 14, or 24 per cent., are peculiar to or entogenic in the region^. The principal portion of the fauna is supplied by the development of the twelve Holarctic genera shared in common with Nearctica, viz. Cordiilegaster, Gomphus, Ofhiogomfhus, Boyeria, Somatochlora, Cordulia,Libellula, Sympetrum, Leucorrhmia, Calopteryx, Agrion and EnaUagnia. The development of Anisoptera is on the whole less marked, of Zygo- ptera more marked, than in Nearctica. There are no peculiar genera of Gomphini, and only two of Corduliinae, Oxygaslra (fig. 152) and Efitheca. But in the Zygoptera, there are the ^ See foot-note on p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Tillyard, Robi
Size: 3196px × 782px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublishercambridgeenguniver
