TRANSACTIONS OF WAGNER 



MASTODON 



the last inner lobe. The intermediate buttresses exhibit more or less disposi- 

 tion to extension in the valleys as tubercular ridges between the outer lobes. 

 The disposition is really more strongly marked in the right tooth. At the 

 back of the crown is a broad pyramidal talon springing from the basal ridge, 

 and divided into a row of mammillary eminences. The basal ridge is well 

 developed internally, and is continuous with the thicker portions in front and 

 behind the crown. The first and second outer lobes are subdivided into two, 

 and the outer portion of the second is again divided at its summit. The third 

 outer lobe towards the summit divides into three eminences. 



In these teeth all the lobes are worn except the last outer one. The right 

 tooth is more worn than the left one. The pairs of lobes are worn across in 

 inclined planes nearly to a level, sloping in front and behind on the anterior 

 two pairs of lobes, but in front only on the posterior pair. Shield-shaped 

 areas of dentine are displayed on the anterior two inner lobes. In the left 

 tooth, as seen in fig. 2, elliptical areas of dentine are displayed on the inner 

 subdivisions of the anterior two outer lobes. In the right tooth the first outer 

 lobe displays a pair of elliptical dentinal areas, and the second outer lobe a 

 transverse row of three smaller areas. An elliptical islet of dentine occupies 

 the extension of the anterior buttress of the crown in both teeth. The enamel 

 of the summit of the last inner lobe is worn in an inclined plane forward, but 

 the dentine is not exposed. The contiguous outer lobe exhibits no trace of 

 wear. A moderate layer of cementum, pretty evenly deposited, occupies the 

 deeper recesses of these teeth. 



The measurements of the teeth are as follows : 



Right tooth. Left tooth. 



Fore and aft diameter of .the crown . . 148 mm. 



Transverse diameter at base of anterior lobes . 95 mm. 92 " 



Transverse diameter at base of middle lobes . 88 " 89 " 



Transverse diameter at base of posterior lobes 88 ' ' 



Height of the last outer lobe, unworn . . 66 " 



The crown of the upper right last molar tooth, represented in plate v. fig. 

 2, is complete, but the fangs are broken away. The tooth had barely pro- 

 truded at its fore part, and is abraded from use only on the summit of the 

 first external lobe. The front of the crown at its base exhibits the result of 

 pressure or friction of the adjacent second true molar. The crown is com- 

 posed of four pairs of lobes, springing from a broad base, with a conspicuous 

 tubercular talon. It is widest opposite the first pair of lobes, slightly narrow 

 at the next pair, then more abruptly at the third, and is more gradually 



