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Show 178 MR. F. E. BEDDARD ON THE [Apr. 6, 1. On some Points in the Anatomy of Chauna chavaria. F R A N K E. BEDDARD, M.A., F.R.S.E., F.Z.S., Prosector to the Society. [Keceived March 15, 1886.] Prof. Garrod has contributed to the ' Proceedings ' of this Society some notes upon the anatomy, more particularly of the soft parts, of Chauna derbiana l. The recent death of one of the Society's specimens of Chauna chavaria has enabled me to supplement Prof. Garrod's observations by some notes on the structure of the second species of Chauna. As might have been expected, there are no great differences between the two species; and with the exception of the colic caeca and the distribution of the tracheal muscles, all the statements made by Garrod apply equally well to the present species ; with regard to the visceral anatomy I am not able to institute a detailed comparison between the two species, since certain of the facts which I shall describe in the present paper have not been referred to by Garrod in his account of Chauna derbiana. To these facts I have paid particular attention in order to render more complete our knowledge of this interesting bird. Air-sacs, fyc.- O n opening the body-cavity it was seen to be completely separated into a right and left half by a vertical septum attached above to the sternum and the ventral wall of the abdomen, and below to a horizontal fibrous septum which will be presently described. This vertical septum anteriorly separates the two lobes of the liver and runs as far forward as the pericardium ; it corresponds to the umbilical ligament, a structure which has not usually so great an extent in birds ; more generally the umbilical ligament only extends as far back as the gizzard and terminates in a semicircular free posterior margin. In Chauna this vertical ligament bears a blood-vessel which joins the portal system anteriorly and posteriorly divides into two trunks, one of which passes further back than the other; this vessel is situated near the dorsal attachment of the septum. The horizontal septum is an extremely thick brown-coloured membrane which passes across the abdominal cavity from side to side, and completely covers the coils of the intestine, being attached laterally to the walls of the abdomen. This tough brown membrane corresponds to a structure described by Weldon (P. Z. S. 1883, p. 640) in tbe Storks, and by myself (P. Z. S. 1885, p. 841) in the Cranes and other birds. This horizontal membrane when it reaches the gizzard splits into two layers which form a complete covering to that organ ; between it and the gizzard, on the inferior surface of the latter, are numerous air-spaces which were easily distended by inflating the air-sacs. The relations of the abdominal viscera are therefore, so far as the presence of this horizontal septum is concerned, indicative of an affinity with the Storks and Cranes, and more particularly with the 1 ' Collected Papers,' p. 318. |
