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Show 1896.] MR. P. E. BEDDARD ON DISSURA EPISCOPUS. 233 Ciconia; and it may be possible to regard it as congeneric with Abdimia, remembering that both are African in range. In any case we have here a distinct relation between structure and geographical distribution. The Storks aud Herons are contrasted by other structures than those to which reference has already been made in the present communication. I desire now to call the attention of the Society to certain structures which have not hitherto been used in this connection, and which indeed have been but little made use of in the systematic arrangement of birds. These characters are drawn Fig. 2. Syrinx of Abdimia sphenorhyncha. from the number and position of the muscles of the lungs, those muscles which usually arise from the ribs and expand over the pulmonary aponeurosis. To the complete set of these muscles the term " diaphragm" has been applied. But at the present moment I a m not concerned with their general morphology, but with their use in detailed classification. It has been stated by Prof. Weldon l that in the Storks " the pulmonary aponeurosis is not muscular." So far as m y experience enables m e to say, that statement is nearly but not absolutely true. In a specimen of Ciconia alba I found a single muscle on each side of the body arising from the most anterior of the ribs bordering upon the lung, and lying just in front of the anterior intermediate air-sae. The rest of the pulmonary aponeurosis was perfectly free from muscles. On the other hand, the Herons are well provided 1 " On some Points in the Anatomy of Phoenicopterus," P. Z. S. 1883, |