ORDER Proboscidea.- This name has been appropriated to a well-marked group of animals, presenting some very anomalous characters, allied in many respects to the Ungulata, but belonging neither to the Artiodactyle nor Perissodactyle type of that order. It has been thought that they possess some, though certainly not very close, affinities with the Rodentia, and also with the Sirenia. It is certain, however, that the two species of Elephant which are the sole living representatives of the order, stand quite alone among existing mammals, widely differing from all others in many parts of their structure, being in some respects, as in the skull, dentition and proboscis, highly specialised, though in others, as in the presence of two anterior vena? cavas and in the structure of the limbs, retaining a low or generalised condition. A considerable series of extinct forms, extending back through the Pliocene and Miocene epochs, show the same type under still more generalised outlines. Though no true Proboscidians have as yet been found in any Eocene formations, certain recently discovered forms of that epoch from North America, if their affinities are rightly interpreted, may link them to some unknown primitive type of Perissodactyle Ungulate. The consideration of these will, however, be reserved until the next lecture.