TEETH. 



871 



denticles, as in the Gdlcopitliecus, blending 

 together into a common base in the fully-de- 

 veloped tooth. 



Fig. 556. 



long diameter of the tooth. When the tooth 

 is bisected vertically and lengthwise, the three 

 substances, d dentine, e enamel, and c cement, 



Fig. 557. 



Section of lower incisor of Galeopithecus 

 (Magnified.) 



A figure is given of the grinding surface of 

 the third true molar of the Phacochosrus Pal- 



Section of molar of Elephant. 



are seen interblended as in Jig. 557., in which 

 p is the common pulp- cavity, and r one of 

 the roots of this complex tooth. 



A still more complex grinding apparatus is 

 found in certain fishes. The lower pharyngeal 

 bone of the parrot-fish (5cffrws*), for ex- 

 ample, supports a dental plate with a tri- 



Fig. 558. 



Ttvo of the upper pharyngeal teeth, Scarus. (Magnified.) 



turating surface like that of the compound 



molars of the Phacochcerus. The interlocked 



upper pharyngeals (fig- 565.) support dental 



* Odontography, pi. 51., fig. 3. 



3X4 



lasli, in PI. 140, Jig, 4, of my " Odontography." 



In the elephant the denticles of the com- 



poimd molars are in the form of plates, vertical 



to the grinding surface and tranverse to the 



