64 



EVOLUTION OF MAMMALIAN MOLAR TEETH 



To begin with the lower molars, the dental cap in the jaw forms 

 a broad, saucer-like surface, and then at the corners of that cap 



Fi<;. 4-J. Developing Upper and Lower Molars of a four weeks old child. Note the resem- 

 blance in the upper molar to the molar of the Eocene Primate in Fig. 40 No. 10. After Rose. 



A 



B 



C 



FIG. 42'. The three Primary Forms of Molar Teeth, secondarily attained in three modern 

 forms. A, Haplodont, of the Dolphin. B, Triconodunt, of the Leopard Seal, Ogmorhinus 

 l< /itvni/.i: C, Tritubercular, of the Cape Mole, Chrywhlorin (see p. 125). 



calcified points appear (Fig. 42*). In what order (Fig. 1) do they 

 appear I The order is shown in the following table : 



COMPARISON OF EVOLUTION AND EMBRYONIC DEVELOPMENT. 





UPPER MOLARS . 



LOWER MOLARS . 



Order by "Cusp 

 Addition' Theory." 



1. Anterior palatal. 



/ Anterior buccal. 



\ Posterior buccal. 

 4. Posterior palatal. 



2. 



1 . Anterior buccal. 



2. Anterior lingual. 



3. Posterior buccal. 



4. Posterior lingual. 



5. Posterior mesial. 



Order of Embryonic 

 Development. 



1. Anterior buccal. 



2. Anterior palatal. 



3. Posterior buccal. 



4. Posterior palatal. 



1. Anterior buccal. 



2. Anterior lingual. 



3. Posterior buccal. 



4. Posterior lingual, 



5. Posterior mesial. 



