177 



female Mastodon. The direction of the ridge circumscribing' the insertion 

 of the temporal muscle, shows this to have extended deeper upon the outer 

 part of the ascending ramus than in the younger specimen, No. 715. 

 From the tertiary deposits of Ohio. Purchased. 



72 1 . A portion of the right ramus of the lower jaw of the Mastodon giganteus ; 

 with the last molar tooth much worn : it has supported five transverse 

 ridges, the last of which alone retains its mammillary divisions : behind 

 these there is a small tuberculate talon. The common dentinal base of 

 the first and second ridges is exposed by attrition and worn into a 

 smooth and polished cavity. One of the outlets of the dental canal is 

 situated, as usual, below the alveolar border, in advance of the last molar : 

 the large size of the remainder of the canal, which is continued to the 

 fractured end of the symphysis, and its proximity to the inner margin of 

 that part, indicates very strongly the existence of the incisive tusk on 

 this side of the jaw, and that this fragment belonged, therefore, to a male 

 Mastodon. 



From the tertiary deposits of Ohio. Hunterian. 



722. The last upper molar of the Mastodon giganteus : its crown, which re- 



sembles that of the preceding specimen, is supported by two large anterior 

 diverging fangs and a posterior mass divided by deep longitudinal de- 

 pressions into six lobes or divisions. 



From the tertiary deposits of Ohio. Hunterian. 



723. The last upper molar of the Mastodo?i giganteus. The crown supports 



four transverse ridges and a posterior talon : each of the ridges is divided 

 into two nearly equal mammillae, and there is a small tubercle at the 

 outer part of each of the three interspaces : the base of the tooth is sub- 

 divided into seven fangs. 



From the tertiary deposits of Ohio. Purchased. 



724. The last upper molar of the Mastodon giganteus ; its crown supports five 



transverse ridges, an anterior basal prominence and a posterior talon : it 

 is supported by a mass, more or less completely subdivided into seven 

 fangs. 



From the tertiary deposits of Ohio. Hunterian. 



2 A 



