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Show 186 MR. F. E. BEDDARD ON THE CUCKOOS. [Feb. 1 7, organ. In Geococcyx, Centropus, Pyrrhocentor, and Coua1 the syrinx is somewhat intermediate between the bronchial and the tracheo-bronchial, but on the whole appears to m e to present more resemblances to the former. The continuation of the membrana tympaniformis up to the bifurcation of the bronchi, and the presence of a well-marked pessulus undoubtedly are points which characterize the tracheo-bronchial syrinx; on the other hand, the extreme narrowness of the membrana tympaniformis in the anterior half of each bronchus, and its sudden widening out at that bronchial semiring upon which the intrinsic muscles of the syrinx are attached, indicates that the syrinx of these genera is only separated by a very small interval from the bronchial syrinx of Crotophaga. A complete closure of the already very narrow interval separating the inner ends of the anterior bronchial semirings would bring about a syrinx entirely indistinguishable from that of Crotophaga ; in the ordinary tracheo-bronchial syrinx the membrana tympaniformis is widest anteriorly, and, if anything, diminishes posteriorly. Guira and Crotophaga further present an agreement with each other in having eight rectrices instead of the ten which characterize all the other genera of the family known to me2. The tracheo-bronchial syrinx of Eudynamis and Phcenicophaes, combined with the Centropine characters exhibited in the pterylosis, appear to m e to necessitate their separation both from the Cuculine and the Centropine forms. The muscle-formula of these two genera (seep. 170) is complete; and so far they agree with the Centropine and differ from the Cuculine genera ; they should perhaps form a third subfamily equivalent to either of the other two. The following table of classification will serve at least as an abstract of the facts contained in the present paper, and of the conclusions respecting the mutual affinities of the different genera, to be derived from a study of these facts. I do not of course pretend that as a system of classification it will be permanent; but it may at any rate be an assistance towards a proper classification, which can only be drawn up when all the genera have been thoroughly studied. 1 I have not myself examined Coua, but I possess sketches of its syrinx drawn by Mr. Garrod from specimens lent to him by M . A. Milne-Edwards. It is but fair to m y predecessor to mention also, that several of the other syringes described in the present paper have been carefully drawn by him. The woodcuts which illustrate this paper are not, however, copied from Mr. Garrod's sketches, which only came into m y hands after the woodcuts bad been already drawn by Mr. Smit. 2 Mr. Sclater particularly associates these two genera in his ' Catalogue of American Birds,' p. 320. |