Bulletin Volume 124

Bulletin Volume 124

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 edition. Excerpt: ... both recent and fossil, will prove whether four branches of a median vein are ever present, and if both M3 and M4 really occur, in what order and manner they have disappeared. The ordinary course of reduction of Media is further shown in the figure at h, i, j, k, l, none of which is hypothetical. In i, vein M3 is about equally supported at its base upon its deflected base and the median cross vein, and when either support disappears, naturally it is the cross vein that disappears as a irule. But the exceptions are shown at m, n, o and p of the diagram, in which the deflection at the base disappears, leaving 1 It is shown particularly well in an undescribed Holorusia in my collection from the Cameroons. M3 attached to M1+2 by the cross vein, and often remarkably simulating a real M2. After this shift, it may fuse with M1+2 as shown at n, or its base may recede to simulate a deepening fork, as in Mesocyphona pi. 23, fig. 3 as at 0, and the base of M1+2 may even be deflected upward to enter more strongly into the composition of the cord as at p, Amphineura pi. 9, fig. 6. There are some minor shifts of parts that occur sporadically; the foregoing are the general tendencies. Cell 1st M2 is shifted very far inward in Lechria pi. 9, fig. 5, very far outward in Oropeza pi. 16, fig. 3 and Paratropeza pi. 28, fig. 4. The hind margin of the wing is beautifully scalloped in Dapanoptera pi. 28, fig. 3. There is a striking decurvature of veins at the tip in Libnotes pi. 28, fig. 5, 6. The base of the radial sector is strongly bent in Paratropeza pi. 21, fig. 4, and more sharply, and with a most curious compensatory adjustment of R2+3 in Goniodineura, pi. 28, fig. 2. And there are endless other less striking peculiarities of venation occurring here and...show more

Product details

  • Paperback | 176 pages
  • 189 x 246 x 10mm | 327g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236823249
  • 9781236823243