NOTES ON A NEW FOSSIL MAMMAL. ]1 



the ElephantidiB they appear either only in the upper jaw as seen 

 in Elephas, Stegodon and many species of Mastodoiu or in both jaws 

 as in some other species of Mastodon. 



(2) In the Dinotheridœ the grinding surface of the molars is 

 provided with very simple transverse ridges which are three in 

 number in the first molar, and two in the other molars, and are 

 entirely destitute of cement ; while in the Elephantidte the construction 

 of the teetli is more complicated. Some species of Mastodon, in 

 which the teeth sIk^w a very simple construction, have two or more 

 transverse ridges with somewhat deeper valleys, and also sliow a 

 tendencv for each ridi2:e to divide itself into a rii>ht and a left half, 

 while most frequently these ridges are further subdivided into 

 tubercle-like bosses. In Elephas the ridges become very numerous 

 and are separated from one another by deep cleft-like valleys filled 

 with thick cement, while in Stetjodon the teeth present the transi- 

 tional form between those of Eleplias and Mastodon. 



(3) In the Dinotherida^ all the teeth (two {a-emolars and 

 three molars) are simultaneously functional, while in the Elephan- 

 tidie there are no more than one or two in place and in use at 

 all times. 



Xow examining the Japanese specimens, there are many 

 characters which distinguish them from the two fomilies above 

 described. Indeed the distinction is quite as great as that existing 

 between these two. The Japanese form has a great number of 

 incisors, viz., one pair in the upper jaw and two pairs in the loAver. 

 Although the specimens seem to belong to a young form and the 

 incisors are not yet perfectly developed, there is reason to beheve that 

 they will not develop so strongly as to form tusks which are seen in 

 the above two families. In the fact that the premolars and molars are 

 all simultaneously functional, they resemble Dinotherhim, while their 



