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Show 1895.] ANATOMY OF CHAUNA CHAVARIA. 353 Windpipe. I have little to add to Beddard's description of this organ (3). The two pairs of extrinsic muscles were as he found them. The syrinx was notched only at the back, as in C. derbiana. None of the bronchial semirings were ossified. The Heart. This organ was typically avian. The only peculiarity worth noting was in the right auriculo-ventricular valve. In the smaller part of the valve, which Beddard and I have identified with the septal flap of the Alligator's similar valve, I found a small tendinous area. The edge of the flap was muscular, one strand of muscle running to the bridge of muscle which binds the two flaps to the wall of the ventricle. Another band of muscle passed from the lower edge of the valve to the septal wall of the ventricle, exactly as in the Ostrich and in the Alligator. Tlie Buccal Cavity. The tongue was identical with that of G. derbiana, as described by Garrod. Between the rami of the mandible, anterior to the mylohyoid anterior, lay a pair of large pear-shaped glands opening into the floor of the mouth at the anterior end, just behind the lower beak, by a number of small apertures on each side of the middle line. MVOLOGY. In m y account of this I shall follow the description recently given by Beddard and myself of the myology of Palamedea (2), as in the main the two birds are very closely alike. In the muscles of the neck and trunk the only point worth noting is that the new muscle described by us as the costo-sternalis externus was also present in Chauna chavaria. It arises by a flat tendon from the third, fourth, and fifth ribs and is inserted to the costal edge of the sternum, less than half an inch from the posterior end. As in Palamedea it m a y be taken as replacing physiologically, to a certain extent, the absent uncinate processes. Head-Muscles. Dermo-temporalis and biventer maxillae as in Palamedea. Digastric or depressor mandibular, as in Palamedea, consists of two parts. The external portion arises by a strong tendon from behind the external auditory meatus; it runs downwards and forwards, and is inserted fleshy along the upper edge of the angulare. The inner portion is almost entirely tendinous ; its origin is below that of the outer portion and its insertion is to the ventral and median side of the origin of the angular process. Temporalis consists of four clearly separated portions. The PROC. Z O O L . Soc-1895, N o . XXIII. 23 |