24S ON THE EXTINCT MAMMALIA OF 



XXVII. In its form, constitution, condition of preservation, and color, it sufficiently 

 I'eseinbles the corresponding portion of the enigmatic tooth purchased in London as to 

 render it more probable than ever that the latter is really American. The fragment, 

 while approximating most the corresponding part of the enigmatic tooth, also 

 approaches that of the cast, so as to be intermediate in character. 



The accompanying fragment of a tooth consists of a middle portion of the crown, 

 which in the arrangement of its constituent elements sufficiently resembles the other 

 specimen to belong to the same species, if not the same individual. 



Two additional specimens in the Museum of the Academy may perhaps belong to 

 the same species as the foregoing. One of these consists of the fragment of a Mastodon 

 molar from the collection of the American Philosophical Society. It is represented 

 in figures 3, 4, plate xxii, accompanying Dr. Hays' " Descriptions of Inferior Maxil- 

 lary Bones of Mastodons," in the fourth volume of the Transactions of that Society. 

 Is is indicated in the reference to the plate as belonging to a peculiar species, and is 

 dedicated to Dr. Chapman, from which it is usually referred to under the name of 

 M. Chapmani. Nothing is known in regard to the locality from whence the specimen 

 was obtained. Apparently it consists of the fore part, comprising three divisions, of 

 the last upper molar of the right side. It is much worn, and the embracing enamel 

 of the first division of the crown, together with the greater part of the outer lobe of 

 the second division, are broken away. / 



In the anterior two divisions of the crown the exposed dentine extended in single 

 broad tracts from side to side. In the less worn third division the lobes yet remain 

 distinct, and appear to alternate with each other in relative position. The inner 

 lobe, worn, like those in advance, nearly to the bottom of the intervening portion 

 of the transverse valleys, occupies nearly two-thirds of the masticating surface of 

 the third division of the crown. Its exposed dentinal tract is transversely dumb-bell 

 formed, with the interior portion festooned. The outer lobe, posterior and external 

 in position to the inner lobe, is bounded in front and behind by the deep outlets of 

 the contiguous transverse valleys. A groove indicates it to be composed of a connate 

 pair of lobules, the summits of which together exhibit a transverse dumb-bell-like 

 tract of dentine, much smaller than that of the inner lobe. Behind the latter, in the 

 middle of the third valley there is an accessory eminence, worn to the level of the 

 lobes in advance, and exhibiting on its summit a small oval islet of dentine. 



The remaining specimen above referred to consists of the fragment of a Mastodon 

 tooth from the excavation of the Brunswick Canal, Darien, Georgia, where it was 

 found in association with remains of Elephas Columhi, Megatherium mirabile, Equtbs 

 fraternus, Bison latifrons, etc. 



The fragment apparently consists of the posterior two divisions of the crown of a 

 fifth molar, and resembles in general form the corresponding portion of the same tooth 



