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Show 82 mmal save one-as different a creature from Inan as can ma l h . well be imagined-namely, the long extinct Anop ot erzum. The teeth of the Gorilla, on the contrary, exhibit a break, or interval termed the diastema, in both jaws: in front of the eye-too~h, or between it and the outer incisor, in the upper __) )tfan. ma (!ynocep]lalus. X2 FIG. 18.-Lateral views, of the sa~e. length, of the upper jaw~ of. va~!C:~ Pnm. ates .; incisors · c canines · pm~ premolars ; m, molars. A lme IS di through ·t he~ , first mo'l ar ' of Man,' Go1•illa, Cynocephal~s, and .c e b u s, ~n d .t he grinding surface of the second molar is shown in each, 1ts antenor and mtema1 angle being just above the rn of m2 • 83 jaw; behind the eye-tooth, or between it and the front false molar, in the lower jaw. Into this break in the series, in each jaw, fits the canine of the opposite jaw; the size of the eye-tooth in the Gorilla being so great that it projects, like a tusk, far beyond the general level of the other teeth. The roots of the false molar teeth of the Gorilla, again, are more complex than in Man, and the proportional size of the molars is different. The Gorilla has the crown of the hindmost grinder of the lower jaw more complex, and the order of eruption of the permanent teeth is different; the permanent canines making their appearance before the second and third molars in Man, and after them in the Gorilla. Thus, while the teeth of the Gorilla closely resemble those of Man in number, kind, and in the general pattern of their crowns, they exhibit marked differences from those of Man in secondary respects, such as relative size, number of fangs, and order of appearance. But, if the teeth of the Gorilla be compared with those of an Ape, no further removed from it than a Cynocephalus, or Baboon, it will be found that differences and resemblances of the same order are easily observable; but that many of the points in which the ~orilla resembles Man are those in which it differs from the Baboon; while various respects in which it differs from Man are exaggerated in the Cynocephalus. The number and the nature of the teeth remain the same in the Baboo!l as in the Gorilla and in Man. But the pattern of the Baboon's upper molars is quite different frmn that described above (Fig. 18), the canines are proportionally longer and more knife-like; the anterior premolar in the lower jaw is specially modified; the posterior molar of the lower jaw is still larger and more complex than in the Gorilla. Passing from the old-world Apes to those of the new world, we meet with a change of much greater importance than any of these. In such a genus as Cebus, for example (Fig. 18), it will be found that while in some secondary points) such as the projection of the canines and the diastema, the resemblance G 2 |