The Mauer jaw is indeed a most remarkable specimen. The first general outcome of an inspection of the photographs or of the excellent casts (which may now be seen in many museums) is a profound impression of its enormous strength (Figs. 2, 13, and 15_c_). By every part of the specimen save one, this impression is confirmed. This massiveness, together with the complete absence of any prominence at the chin, would have caused great hesitation in regard to the pronouncement of a decision as to the probable nature of the fossil. The one paradoxical feature is the relatively small size of the teeth. All of these have been preserved, though on the left side the crowns of four have been removed by accident in the process of clearing away some adherent earth and pebbles. The net result shews that the teeth are actually within the range of variation provided by human beings of races still extant, though commonly regarded as 'primitive,' if not pithecoid (such as the aboriginal race of Australia). Yet these teeth are implanted in a jaw of such size and strength as render difficult the reference of the specimen to a human being. [Illustration: Fig. 2. _A_ outline tracing of a cast of the Mauer Jawbone. _B_ a similar tracing from an unusually large jaw of an ancient Briton. (From specimens in the Cambridge Museum.)] The most striking features of the Mauer jaw have been mentioned already. Before entering upon a further discussion of its probable nature, it will be well to note some of the other distinctive characters. Thus the portion Fig. 2 (_a_) known technically as the ascending ramus is of great size, and particularly wide, surpassing all known human specimens in this respect. The upper margin of this part is very slightly excavated, a slight depression (_b_) replacing the very definite 'sigmoid' notch found in almost all human jaws (though the relative shallowness of this notch has been long recognised as distinctive of the lowest human types). The difference in vertical height between the uppermost points of the condyle (_c_) and the coronoid process (_d_) is therefore unusually small. On the other hand, the lower margin of the bone is undulating, so that it presents a hollow on each side, as well as one near the middle line in front. The two halves of the bone are definitely inclined to one another and this convergence is faintly marked in the two rows of teeth behind the canines. The latter teeth do not project markedly above the level of those adjacent to them. The incisor teeth are remarkably curved in their long axes, with a convexity in front. The prominences called 'genial tubercles' behind the chin are replaced by a shallow pit or fossa.