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718. The left ramus of the lower jaw of the Mastodon giganteus, with 

 part of the symphysis, the socket of the penultimate molar, and the 

 last molar in situ. The crown of this tooth supports four transverse 

 ridges, and a posterior talon divided into four small tubercles in the same 

 transverse line. 



The great dental canal presents three distinct outlets, one below the 

 socket of the penultimate grinder, the second of equal size near the 

 symphysis, and a third smaller one below and in advance of the preceding : 

 there is no trace of the socket of an incisor. This specimen exhibits a 

 variety of the last molar in its diminished size, as well as in the smaller 

 number of eminences on the grinding surface. 



From the tertiary deposits of Ohio. Purchased. 



719. The left ramus of the lower jaw of Mastodon giganteus, with the last 



molar in situ and the socket of the penultimate one. The crown of the 

 last molar supports five tuberculate ridges and a small posterior tuberculate 

 talon : this molar resembles in structure the last of No. 715 ; but is of 

 smaller size, indicating a variety in this respect, in the Mastodon giganteus : 

 there are two anterior outlets of the great dental canal, one beneath the 

 socket of the penultimate molar, the other of smaller size near the sym- 

 physis, which exhibits no trace of the alveolus of the incisive tusk. 

 From the tertiary deposits of Ohio. Purchased. 



7'20. A portion of the right ramus of the lower jaw of the Mastodon giganteus, 

 including the socket of the penultimate molar and the last molar in situ : 

 the crown of this tooth supports four normal bimammillary transverse 

 ridges ; a large posterior bituberculate talon, which might be regarded as 

 a fifth ridge; and a smaller talon behind this : there is a small tubercle at 

 the outer antjle of the interspace of each of the transverse ridges, and 

 the third tubercle of the large posterior talon represents one of the same 

 series in the interspace between that talon and the fourth normal ridge 

 of the crown. The summits of the outer mammillary processes are 

 worn down lower than those of the inner ones : portions of three of the 

 fangs of this molar are exposed. The absence of an alveolus for the in- 

 cisor at the symphysial end of this ramus, indicates it to have belonged to a 



