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Show 1891.] BOTALLI IN CERTAIN BIRDS. 177 Within the last few months I have come upon two cases of abnormality similar to the above, but still more marked, inasmuch as instead of a cord a functional vessel was present. In the first instance, which occurred in a Violaceous Night-Heron (Nycticorax violaceus), the deviation from the ordinary arrangement was very marked, as is well shown in the figure, which was drawn from the injected specimen by Mr. Harrison, under my supervision. The right carotid was very large at its origin, and ran for about an inch towards the left (this portion of the vessel being marked in the figure by an asterisk), when it turned almost at right angles and ran forward in the usual manner, giving off at the turning point the right vertebral, and a rather larger vessel which ran back to join the dorsal aorta at the base of the heart. In the figure the heart is removed, and the aorta pulled forward to show this junction. Injection proved that this connecting duct had a lumen and was thus quite functional, though apparently not of equal B.Ao Carotids of Nycticorax violaceus. Ca, carotids ; V, vertebrals ; B.B, ductus botalli; In, innominates ; B.Ao, dorsal aorta. The * marks the enlarged part of the right carotid. calibre throughout. The vertebrals (V, V), though given apart, reached the spinal column at about the same point; nor did I observe any abnormality in the vessels of the left side. PROC. ZOOL. Soc-1891, No. XII. 12 |
