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Show 1876.] OF PASSERINE BIRDS. 513 Through the kind permission of Dr. Giinther I have had the opportunity of dissecting two specimens of each of two species of the genus Pitta, namely P. cyanura and P. angolensis, from the National Collection ; and Mr. Sharpe had previously very liberally given me a specimen of the Javan species, the dissection of which had led me in m y paper " O n the Carotid Arteries of Birds" to remove it from the Oscines *, as Cabanis had done from its wing-characters. Two specimens of Pitta angolensis from Fantee, and three of P. cyanura from Java, have therefore formed the material for the present description. In Pitta angolensis the unmodified trachea terminates thoracically in a ring, split behind, and deep in front; which, from the fact that it presents irregularly placed fenestras on its anterior surface, arranged in a somewhat transversely linear manner, appears to have been formed by the fusion of two rings. This terminal segment of the trachea does not, as io the Oscines and several other Passeres, form a three-way piece, because there is no antero-posterior bar traversing its inferior margin in the middle line. Of this, however, there is an indication in the form of a median backward-directed process, which advances a short distance into the inferior membrani-form completion of the tube, from its anterior border. The tracheal ring last but one is complete, and has a slight median indentation in its inferior margin behind. These points are seen in Plate LIII. figs. 1, 2, & 3. The first and second bronchial ring-segments are semirings-not modified into the somewhat separate, round-margined, slightly oblique semicircles of fibro-cartilage or bone which, as usual, are found nearer the lungs, but are like moieties of true tracheal rings, approximate, sharp-edged, and at right angles to the axis of the tube. They present no peculiar processes, and are slightly swollen at their anterior extremities. There is only a single pair of bronchial muscles, continued down from the sides of the windpipe; insignificant in size ; quite lateral, and terminating by being inserted into the middle of the outer surface of the second bronchial semiring. Pitta cyanura differs from P. angolensis only in detail, not in plan of conformation. There are four instead of two syringeal bronchial semirings, to the middle of the last of which the single extremely feeble lateral muscle is attached on each side. In it also the last two tracheal rings, and not the last only, are incomplete behind, the last presenting a greater gap than the one above it. This syrinx is figured in Plate LIII. figs. 4, 5, & 6. Pitta is therefore mesomyodian, in which respect it differs from all the known Old-World Passeres-although Philepitta, with its lengthy first primary, is most probably the same iu this respect. With reference to other points in the anatomy of the genus, it may be mentioned that in both Pitta angolensis and P. cyanura there is but one carotid artery, the left. The oil-gland is nude. The colic caeca are between one eighth and one tenth of an inch in * P. Z. S. 1873, p. 463. |