. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 920 TEETH. with, and contributes to, the straight line which the canine and premolars form with the true molars. The true molars (, in. l,, ???.3)are quadricuspid, relatively larger in comparison with the bicuspids than in the Orang. In the first and second molars of both species of Chimpanzee a low ridge connects the antero- internal with the postero-external cusp, cross- ing the crown obliquely, as in Man. There is a feeble indication of the same ridge in th0 unworn molars of the Orang ; but the four princi
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 920 TEETH. with, and contributes to, the straight line which the canine and premolars form with the true molars. The true molars (, in. l,, ???.3)are quadricuspid, relatively larger in comparison with the bicuspids than in the Orang. In the first and second molars of both species of Chimpanzee a low ridge connects the antero- internal with the postero-external cusp, cross- ing the crown obliquely, as in Man. There is a feeble indication of the same ridge in th0 unworn molars of the Orang ; but the four principal cusps are much less distinct, and the whole grinding surface is flatter and more wrinkled than in the Chimpanzee. In the Troglodytes niger the last molar is the smallest, owing to the inferior development of the two hinder cusps, and the oblique connecting ridge is feebly marked. In the Troglodytes Gorilla this ridge is as well developed as in the other molars, but is more transverse in position ; and the crown of m. 3 is equal in size to that of m. I or m. 2, having the pos- terior outer cusp, and particularly the pos- terior inner cusp, more distinctly developed than in the Troglodytes niger. The repe- tition of the strong sigmoicl curves which the unworn prominences of the first and se- cond true molars present in Man, is a very significant indication of the near affinity of the Chimpanzee as compared with the ap- proach made by the Orangs or any of the inferior Quadrnmana, in which the four cusps of the true molars rise distinct and indepen- dently of each other. A low ridge girts the base of the antero-internal cusp of each of the upper true molars in the male Chimpan- zee: it is less marked in the female. The premolars as well as molars are severally im- planted by one internal and two external fangs, diverging but curving towards each other at their ends as if grasping the substance of the jaw. I have found the two outer fangs of the second premolar connate in one f
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