A Genealogic Study of Dragon-fly Wing Venation

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U.S. Government Printing Office, 1903 - Odonata - 62 pages
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Page 705 - The Wings of Insects, Amer. Nat, XXXII and XXXIII, 1898 and 1899; Art, Odonata, XXXII, pp. 903-911, 9 figs. c The only preparation necessary to demonstrate the facts cited in the following pages is that of the wings of nymphs, which should be removed fresh, mounted quickly in glycerin jelly, and cooled suddenly (to retain the air in the tracheae), and...
Page 749 - in which nodus and quadrangle become more and more approximate, and the veins Mz, Rę, and Mi migrate separately along vein Mi from their accustomed places toward the stigma.
Page 735 - In ^Eschna and its nearest allies (Plate XL) we see the further progress of these tendencies. There is this added feature — the radial sector has become forked. It will be observed that the anterior branch of this fork is separated from vein M% by a single row of cells, and that in the same place in Basiseschna (Plate XXXVII, fig.
Page 730 - In the Zygoptera this tendency is more evident in the antenodals than in the postnodals, the latter never becoming so few, absolutely, or relatively to the antenodals, as in certain Anisoptera, eg, Pachydiplax (front wing: antenodals 6, postnodals 6) or Miathyria simplex (front wing: antenodals 7...
Page 707 - The radial sector. — In the adult wing (fig. 3) the radial sector appears to be a branch of the media. It has always been so interpreted. The only indication of its connection with the radius is the persistent obliquity of an apparent cross vein between veins J/2 and Rs. This is in fact not a...
Page 703 - It is an application of the ir.ethods of comparative morphology to the interpretation of some external characters universally employed in systematic work upon insects. The richly veined wings of dragon-flies have been carefully studied by many able entomologists; their interesting peculiarities are well known; the homologies of the various parts of the wing have been determined throughout the order; and there already exists a considerable body of evidence as to the nature and extent of variation...
Page 749 - In 1903, Professor Needham associated it with the Anormostigmatini ( = legion Pseudostigma of Selys), stating that "it has all the essential venational characters of this group, and surely these are sufficiently distinctive."17 A comparison of Thaumatoneura with these essential venational characters18 gives the following result.
Page 710 - THE NODUS. Here at once we come upon very peculiar wing features. The nodus is the stout cross vein near the middle of the costal border of the wing, joining the costa, the subcosta, and the radius. It is traversed...
Page 758 - ... of first importance. (d) I have been able to indicate many new minor lines of specialization within the order, and to add new and corroborative evidence to some lines already indicated by Kolbe, Karsch, and Calvert. Owing to the presence in these wings of a number of characters which may vary independently, for each of which primitive conditions are easily determined, and in each of which the several courses of specialization are easily traced, 1 have often been able to put forth conclusions...
Page 723 - ... at the present time. The second, rather than the first, is characteristic of those modern genera which belong to the cooler regions of the globe. The first is often accompanied by very abundant

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