OCR Text |
Show 1896.] ON THE OBLIQUE SEPTA IN THE PASSERINES. 225 with which this takes place seems wonderful and to me somewhat analogous to crystallization in inorganic matter. If the elytra are examined from their upper surface, the difference between the larger punctures surrounding the spots and those of the groundcolour is very marked, the latter being irregularly and the others regularly placed ; but if the elytra are removed and examined from the inner side, a thin layer of skin covers the entire surface, but the punctures shine through it and seem of nearly equal size and much more numerous. I may further mention, that all the spots or bands on the upper surface seem slightly convex and show rarely any punctures except round their margins. These are all the observations I am able to record; and I must leave to anatomists to form any conclusions, if such are possible, as to the way in which nature has worked here, and whether we could obtain any clue by examining the insect in its native place, when immature and in process of formation, so as to get some idea how colour, so distinct from punctuation, can influence the latter or the reverse, when this is apparently the case in so exceptional an instance as the present. The subject itself is not new, having been noticed by Chapuis and myself some years ago, but I think it well to draw attention to it again, so that more observations may be made, if possible. 4. On the Oblique Septa (" Diaphragm " of Owen) in the Passerines and in some other Birds. By F R A N K E. B E D D A R D , M.A., F.R.S., Prosector to the Society, Examiner in Zoology and Comparative Anatomy to the University of London. [Received December 16, 1895.] The facts which I bring before the Society have been accumulating in m y notebook for the last few years, and even now there are numbers of types of Passerine birds which I have not had, and may never have, the opportunity of examining. Less emphasis, therefore, must be laid upon such classificatory conclusions as I venture to bring forward, than upon the actual facts which I record. There are a certain number of desirable Passerine genera represented in the rich spirit stores of the Prosector's department, but not referred to in the present paper; I have thought it unwise to make any use of them, since fresh material is so essential for the proper study of delicate and transparent membranes. The greater part of the present communication deals with the divergent structure of what Prof. Huxley1 has termed the " oblique septum" in Passerine birds. I may therefore conveniently commence with a description of the normal arrangement of this structure, as it is seen for example in the Duck. And I avail myself of Prof. Huxley's own words2:-" The second so- 1 " On the Respiratory Organs of Apteryx," P. Z. S. 1882. 2 Loc. cit. p. 561. PROC. ZOOL. Soc-1896, No. XV. 15 |