250 ALLEN S NATURALISTS LIBRARY. 



Besides these external characters, we find, on examining their 

 bony structure, much variation in the skull. Some have a 

 rounded forehead, the ascending portion of the lower jaw 

 being high, broad, and flat, with a large facial angle ; in others, 

 we have great production of the upper jaw (the horizontal part 

 of the lower jaw being greater than the ascending portion), 

 and a low facial angle. The cerebral portion of the skull is long 

 and flattened, and the palate long and narrow. The dental 

 formula is If, C}, Pf, Mf = 32, that of the milk-teeth If, Cj, M 

 (the forerunners of the permanent pre-molars) |=2o, exactly 

 the same as in a Man. The outer lower incisors are equal to, 

 or sometimes smaller than, the inner pair. The permanent 

 canines which are long and sharp come in before, or with the 

 posterior molars of both jaws. Between them and the incisors 

 above, and between the canine and the anterior pre-molar be- 

 low, occurs a gap (or diastema). The anterior upper pre-m( lar 

 has its outer cusp modified and sharpened; the anterior 

 lower pre-molar has the anterior margin of its crown so shaped 

 as to work "as a scissors'-blade against the posterior edge 

 of the upper canines." (Henley?) The crowns of the molar 

 teeth are long from before backwards, and their fore and 

 hind cusps are united by transverse ridges, a third being 

 present in the same genera, on the posterior lower five-cusped 

 molar. 



The nasal bones are often ossified together to form one 

 bone. The surface of the skull is in general oval and smooth, 

 but in some of the Baboons there appear strong ridges over 

 the eyes (hiding the forehead) and along the top of the head, 

 being stronger, when present, in the male than in the female. 

 The external orifice to the ear has a considerable bony tube, or 

 meatus, a distinguishing character which is absent in the New 



