. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. Fig. 21. Base of fore-wing of Thore gigantea Selys. Ax thickened antenodal; Ms Zygopterid sector. Adapted from Needham. We have seen that, if the level of the arculus be very close to the level of the bifurcation of Cu, the quadrilateral will be very short. Such a condition also suggests the possibility of a new arrangement, whereby the arculus, by assuming a sufficient slant, might be continued directly on to the point of division of Cu. In this case the lower portion of the arculus would not be needed as a support, and s
. The biology of dragonflies (Odonata or Paraneuroptera). Dragon-flies. Fig. 21. Base of fore-wing of Thore gigantea Selys. Ax thickened antenodal; Ms Zygopterid sector. Adapted from Needham. We have seen that, if the level of the arculus be very close to the level of the bifurcation of Cu, the quadrilateral will be very short. Such a condition also suggests the possibility of a new arrangement, whereby the arculus, by assuming a sufficient slant, might be continued directly on to the point of division of Cu. In this case the lower portion of the arculus would not be needed as a support, and so the discoidal cell would remain open basally. The Jurassic subfamily Tarsophlebiinae (fig. 158) adopted this line of development. Quite recently, as the result of extreme reduction,. Fig. 22. Wings of Hemiphlebia mirahili.* Selys, (J (hind-wing 11 mra.). 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, Robin John, 1881-1937. Cambridge [Eng. ] : University Press
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