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Show 120 ON CHLAMYDOPHORUS TRUNCATUS. [Feb. 19, Before leaving the salivary glands, it may be mentioned that in the Sloth the socia parotidis (text-fig. 19, sp.gl.) is very large and of unusually definite shape. It is a long pear-shaped body situated at some distance dorsal to Stensen's duct, into which it opens by a single duct 9 ram. in length, that emerges from its anterior pointed end. The Heart.-I have nothing to add to Hyrtl's description of the heart, and I find in two specimens that the great vessels rise from the aortic arch in a manner similar to that previously recorded ; but there is a slight peculiarity in the conformation of the arch itself that merits a brief description, not so much for its intrinsic importance in Chlamydophorus, as because a similar though exaggerated modification forms a very striking feature in the aorta Text-fig. 20. Heart of Three-toed Sloth ( Bradypus tridactylus). of the Sloth. The peculiarity in question consists of a marked depression of the transverse part of the arch towards the ventral surface. The ascending aorta is short, and at the commencement of the transverse part bends sharply forward towards the ventral surface of the heart, and then curves round towards the dorsum compressed between the base of the heart and the trachea. The convexity of the arch thus lies in the transverse plane of the heart, instead of approximately in its longitudinal plane as is usually the case. In two other Edentates (Tamandua and Myrmecophaga) that I have examined, the arch lies in the longitudinal plane as usual, but in the Sloth (Bradypus tridactylus) there is a ventral depression of the aortic arch of a most marked character (text-fig. 20). In both cases, the depression appears to be due to the pressure of |