and of other Animals, found on the left Bank of the Irawadi. 371 



which the tooth of the mastodon is distinguished from that of the elephant, 

 the crown of the tooth wears away more like the tooth of the elephant than 

 that of the other mastodons ; and when worn, exhibits a surface not unlike 

 that presented by the worn tooth of an Asiatic elephant. 



These observations will not, it is hoped, be deemed out of place ; for many 

 a link in the chain which the zoologist who confines himself to the study of 

 living animals only seeks in vain, may be found in the relics of a former state 



of animal life. 



e 



I now proceed to a description of the species, and shall begin with the cha- 

 racter of 



Mastodon latidens. — M. dentibus molaribus latissimis, denticulis rotundatis, 

 elevatis ; palato valde angusto. 



Dentition. — Each tooth of the lower jaw consists of seven denticules, which 

 are elevated, rounded, and mammillated : the mammillse being from three 

 to four in number. The dentition both in this species and in M. elephan- 

 toides, very much resembles that of the elephant. We have the molar tooth 

 gradually protruded forward, and rising as the fangs are added, according 

 to the demand made by the abrasion of the exposed crown, and the conse- 

 quent absorption of the anterior fang ; the posterior part of the tooth not 

 having cut the gum, while the anterior portion is completely worn away. The 

 relics of the preceding tooth, the place of which the tooth in use was progres- 

 sively supplying, are plainly to be seen *. 



The exposed grinding surface is considerably larger than that of the molar 

 tooth of any elephant which I have seen, especially in breadth ; and the ena- 

 mel of the tooth is not so thick as it is in M. giganteum. And here we 

 cannot fail to be struck with the similarity which the worn surface bears to 

 the worn surface of an elephant's tooth. — The denticules are less elevated 

 than those of other mastodons, and the whole form indicates an approach to 

 the structure of the teeth of the elephant. The lower jaw too, in this species, 

 is deeper and less angular than it is in M. giganteum ; and approaches in its 

 contour to the form of the lower jaw of the elephant. But on examining the 

 cranium we shall find still stronger indications of an approach to the elephant ; 

 for the palate is so very narrow when compared with the palate of M. gigan- 

 teum, as to strike the most casual observer f . 



The tusks, judging from the alveoli, must have been of equal volume with 

 the tusks of the largest living elephant. The portions of fossil ivory, however, 



* See Plate XXXVII. fig. 1. Plate XXXVIII. fig. 2. 

 t See Plate XXXVI. and Plate XXXVII. fig. 1. 

 3 c 2 



