. On the anatomy of vertebrates [electronic resource] . p being feebly in-dicated on the ridge extending from the inner side of the first;the crown has also a thick ridge at the inner and posterior part ofits base. The second premolar, p 4, has a subquadrate crown,with the two cusps developed from its anterior half, and a thirdsmaller one from the inner angle of the posterior ridge. Eachlower premolar is implanted by two antero-posteriorly compresseddivergent fangs, one in front of the other, the anterior fangbeing the largest. The three true molars are nearly equal in size in the Troglo-dytes
. On the anatomy of vertebrates [electronic resource] . p being feebly in-dicated on the ridge extending from the inner side of the first;the crown has also a thick ridge at the inner and posterior part ofits base. The second premolar, p 4, has a subquadrate crown,with the two cusps developed from its anterior half, and a thirdsmaller one from the inner angle of the posterior ridge. Eachlower premolar is implanted by two antero-posteriorly compresseddivergent fangs, one in front of the other, the anterior fangbeing the largest. The three true molars are nearly equal in size in the Troglo-dytes Gorilla, the last being a little larger than the first: in theTroglodytes niger, fig. 256, the first, m l, is a little larger thanthe last, m 3, which is the only molar in the smaller Chimpanzeeas large as the corresponding tooth in the black varieties of thehuman subject, in most of which, especially the Australians, , the true molars attain larger dimensions than in the yellowor white races. The four principal cusps, especially the two inner. Teeth of right side, lower jaw, of adult male Chimpanzee, {Troglodytes niger), nat. size. ones of the first molar of both species of Troglodytes, are morepointed and prolonged than in Man; a fifth small cusp is deve-loped behind the outer pair, as in the Orangs and the Gibbons,but is less than that in Man. The same additional cusp is pre-sent in the second molar, which is seldom seen in Man. Thecrucial groove on the grinding surface is much less distinct thanin Man, not being continued across the ridge connecting theanterior pair of cusps in the Chimpanzee. The crown of thethird molar is longer antero-posteriorly from the greater develop-ment of the fifth posterior cusp, which, however, is rudimental incomparison with that in the Semnopitheques and Macaques. All VOL. Ill, Y 322 ANATOMY OF VERTEBRATES. the three true molars are supported by two distinct and well-developed antero-posteriorly compressed divergent fangs; in thewhite
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