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Show 1886.] ANATOMY OF CHAUNA CHAVARIA. 179 former group, since the lobes of the liver are not shut off by septa from the space which lies between tbe horizontal membrane and the ventral abdominal walls. In the Cranes, as in the Struthious birds, the lobes of the liver are enclosed in separate compartments distinct from that underlying the horizontal membrane (cf. P. Z. S. 1885, p. 836). There are other points in which Chauna approaches the Storks. In the paper already referred to, Weldon has drawn attention to a peculiarity in the air-sacs of the Storks which appears to be characteristic of this group, and is at any rate not to be found in the Ducks. The praabronchial air-sacs (in the Storks and Phceni-copterus) are divided by a complicated arrangement of transverse septa into smaller chambers. In Chauna chavaria this subdivision of the praebronchial air-sacs is very much more marked, and the subbronchial air-sacs, which in the Storks and many other birds are fused into a single cavity, are in the same way divided up into an immense number of extremely small chambers, so that the whole air-sac presents the appearance of a crowd of air-bubbles closely pressed together of various sizes. It was quite impossible on this account to distinguish the praabronchial from the postbranchial sacs, that is to say at the points where they come into contact. The prolongations of the subbronchial air-sacs into the axilla and into the space between the two pectoral muscles were similarly subdivided by innumerable septa. There appeared to be nothing remarkable in the disposition of the abdominal air-sacs, and there were no indications of any subdivision of these chambers; the anterior intermediate air-sac communicates with the bronchus by two apertures placed side by side and at some distance from each other near the anterior end of the chamber; in the posterior intermediate sac, which was considerably the larger of tbe two, there was only a single pulmonary orifice. The abdominal air-sacs present the usual character-the right being considerably larger than the left. It appears to be the general rule that the thoracico-abdomiual air-sacs are not divided up in the way that the cervical air-sacs are in Chauna and in the Storks ; but I have met with occasional variations in the structure of their air-sacs in some few out of the numerous birds which I have had the opportunity of dissecting. In Steatornis I have already (supra, p. 151) called attention to the fact that the posterior intermediate air-sac was either completely separated into two distinct compartments or had indications of such a division ; in a specimen of Striae fiammea there was a similar division of the posterior air-sac, at least on one side of the body. The third instance is Platalea leucorodia ; in a specimen of this bird, on both sides of the body there were three "intermediate" air-sacs, the third being very small and interpolated between the anterior and posterior intermediate sacs. This may of course be an abnormality' ; but the air-sacs of birds differ so little that any fact seems worth recording ; and the 1 A second specimen had the normal number of abdominal air-sacs. |