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Show 1894.] VISCERAL ANATOMY OF ORNITHORHYNCHUS. 719 reading the current descriptions of the gut. Though they are not, as O w e n remarks, nearly so close together in the posterior as in the anterior part of the gut, I could detect no oblique disposition of the folds. The Peyer's patches are very slightly developed in this animal; I only found one about 2 feet from the caecum and a second one just below the origin of the caecum. The spleen in the animal dissected by myself was not bifid as it has been described. It was a flat band lying diagonally across the body-cavity and looked almost exactly like a coil of intestine. § Male Generative Organs. Meckel's figure of these organs, which is copied by Sir Bichard Owen, does not appear to m e to be accurate in every particular. The testis is of a loose texture and is enveloped in a tough membrane which can be readily dissected off. This is continuous with a sheet of mesentery which supports the anterior convoluted portion of the sperm-duct. It is not, however, only attached to one side and to only a portion of that, as shown in the drawing of Meckel, but is disposed as in the accompanying drawing (fig. 2, p. 720), an inspection of which will render a detailed description unnecessary. The appearances presented are chiefly due to the fact that the mesorchium is attached to the sperm-duct, not aloug a straight, but a curved line. This brings about the formation of a pocket which is faint comparable to a similar pocket Avhich is usually found between the ovary and the Fallopian tube in female M a m malia. The convoluted character of the sperm-duct is well illustrated in Meckel's figure referred to. It could be readily injected with coloured fluid. § The Heart. The heart of Ornithorhynchus has been so recently described, Avith a full account of the previous memoirs relating to the matter, by Prof. Lankester \ that I need not trouble the Society with any general description. There are, however, some new facts to record concerning the right auriculo-ventricular valve (fig. 3, p. 721). I have thought it worth while to have a drawing prepared of one of the two hearts in m y possession, wdiich differ from each other to some extent. Prof. Lankester found in the hearts examined by himself that the " septal flap " of the valve in the half of the collar which borders the septal side of the ostium Avas either entirely wanting or but slightly represented by a small flap on the right side. This statement was contrary to that of Gegenbaur, who asserted the existence of a complete circular valve like that of other Mammalia. It appeared to Prof. Lankester that the absence or rudimentary character of the septal flap was of greater import- 1 " On the Valves of the Heart of Ornithorhynchus, &c," P. Z. S. 1882, p. 549; and " On the Eight Cardiac Valve of Echidna and of Ornithorhynchus,'' P. Z. S. 1883, p. 8. |
