THE TEETH 407 



is widely open at the apex of each fang. As growth ceases, the fang 

 tapers to a point which is pierced only by a fine opening. 



Having thus gained an idea of the general structure of a typical 

 tooth, the student is prepared to study the entire^, series, beginning with 

 the permanent set. 



THE PERMANENT TEETH. 



^ .3131 



I 1 ormula : % -, c -, pm -, m -. 

 o JL LI _L 



The incisors are the six small teeth planted transversely in the 

 premaxillary bones and the six small teeth which are opposed to them 

 in the mandible below. Each has a single fang, which is relatively 

 long, compressed laterally, and curved backward. 



Of the upper incisors, the first, or inner, is the smallest, and the 

 third, or outer, the largest. 



The crown of the first upper incisor (Fig. 321 ) l is broader in 



FIG. 321. 



Middle Cusp. Middle Cusp. 



Outer Cusp. gjfflrj Inner Cusp. rtrvs Outer Cusp. 

 Talon. of' 



-Fang. If Fang. 



POSTERIOR ANTERIOR OUTER 



ASPECT. ASPECT. ASPECT. 



RIGHT FIRST UPPER INCISOR TOOTH. 



front than behind, and compressed from before backward. The ante- 

 rior surface is slightly convex, and may be pitted. The posterior 



FIG. 322. 



-Middle C"usp.-y Middle Cusp. 



Outer Cusp. ff^g- Inner Cusp. f^ac^- Outer Cusp. 



Neck. - 



Fang. 



POSTERIOR ANTERIOR OUTER 



ASPECT. ASPECT. ASPECT. 



RIGHT SECOND UPPER INCISOR TOOTH. 



surface is divided by a transverse groove into a higher anterior part 

 and a lower posterior part. The anterior chisel-like part when unworn 

 exhibits three cusps, whereof the middle cusp is slightly larger than 



1 For convenience of study and comparison the upper teeth are represented in 

 the figures with their crowns uppermost. 



