430 



MAMMALIAN ANATOMY 



FIG. 353. 



the crown is large and presents a decided anterior cingular cusp, in 

 others it is small and the anterior end is perfectly smooth. In nine 



cases (out of one hundred) 

 the cingulum developed on 

 the inner side a distinct cusp, 

 or deuterocone, which was 

 supported by a separate in- 

 ternal fang (Fig. 353). 



Number. There is no 

 recorded absence of this 

 tooth. Bateson notes and 

 figures (Fig. 354) a specimen 

 which had " a tooth in the 

 upper jaw closely resembling 

 the second premolar internal 

 to and between it and the 

 carnassial. The internal 

 tooth is slightly smaller than 

 the second premolar." 



Form. In one specimen 

 (Fig. 355) the anterior bor- 

 der of this tooth was longer 

 and more oblique than usual, 

 so that the posterior border 

 was vertical and the apex 

 pointed backward as well as 

 downward. The tooth was 



also abnormally placed in the jaw, further than usual in front of 

 the third premolar, with the anterior end of the base of the crown 



A. ABNORMAL UPPER SECOND PREMOLAR TEETH. 



B. THEIR ALVEOLI. 



FIG. 354. 



FIG. 355. 



SUPERNUMERARY LEFT UPPER PREMOLAR TOOTH. 



ABNORMAL RIGHT 

 SECOND UPPER 

 PREMOLAR TOOTH. 



