The anatomy of all marine mammals presents an interesting field of observation upon their structural adaptation to a particular environment, and naturally, therefore, an extensive literature already exists in respect to these mammals, notwithstanding the many difficulties connected with their detailed examination. Their large size and the rapidity with which their tissues undergo decomposition have been serious obstacles in the way of prolonged dissection both of Cetacea and of Seals. Consequently, the examination of many parts of their anatomy has, of necessity, been more or less hurried. Accordingly, in the course of the preparations for the Scottish Antarctic Expedition, led by W. S. Bruce, LL.D., etc., arrangements were made for the preservation of mammalian specimens by the same injection methods that are now commonly used for the practical study of human anatomy, and the medical officer to the Expedition received practical instruction from myself in the application of these methods.