212 COMPARATIVE DENTAL ANATOMY 



canines and true molars in mammals (called bicuspids in 

 man). 



Prognathism. A projecting lower jaw, and a facial 

 angle below 75°. 



Protocone. The primitive reptilian cone of an upper 

 molar, i.e., mesio-lingual cusp; also the buccal cusp or 

 cone of an upper bicuspid or premolar, etc. 



Protoconid. The mesio-buccal cone (or cusp) of a 

 lower molar; also the mesio-buccal cone of a lower 

 premolar. 



Ptenoglossa. A group of gasteropods having teeth 

 only on the sides of the odontophore, but no middle 

 row. 



Ptychodont. Tooth crowns folded on the sides, some- 

 times across the crown. 



Pidp. The soft tissue of vessels and nerves which fills 

 the pulp-chambers and root-canals of a tooth; the rem- 

 nant of the formative pulp. 



Pulp-canal. That portion of the pulp-cavity travers- 

 ing the roots of teeth from the apical foramina to the 

 bottom of the pulp-chambers. 



Quadritubercular. Teeth having four tubercles. 



Quinquetnbercidar. Teeth having five tubercles. 



Rachidian. Pertaining to the rachis or axis. Ap- 

 plied to the central rows of teeth on the odontophore. 



Badida. The dentary organ of mollusks. 



Raphidio-glossa. Needle-shaped teeth on the odonto- 

 phore. 



Ridge. A long elevation on the surface of a tooth 

 crown. 



Root. That portion of the tooth which is inserted in 

 the alevolar process. 



Root-canal. A canal in the center of the long axis of 

 the root which contains the branches of the pulp. 



