CHARACTERS OF STEGODONS. 



83 



the nearly horizontal line of protrusion observable in the 

 most typical Mastodons, snch as the species of North Ame- 

 rica and of Simorre. 6th. In the obverse relation of the 

 planes of detrition of the opposed teeth during wear, the 

 inner side of the upper teeth, and the outer side of the lower, 

 continuing higher in the Stegodons, as in the typical Ele- 

 phants, while the converse holds in the Mastodons. 7th. 

 In the absence or extreme rarity of premolars in both 

 jaws, and of mandibular tusks, neither of which, though 

 occurring among certain Mastodons, have been as yet de- 

 tected among the Stegodons. The aggregate weight of so 

 many points of agreement turns the balance strongly on the 

 side of the Elephants. 



It is deserving of remark, that all the species of the 

 Stegodon group at present known belong to the series indi- 

 cated in the preceding part of this paper, as being of the 

 Dinotherian or Eurycoronine l type, in that the crowns of 

 the molars are broad, the ridges uniformly transverse, and the 

 valleys open, without being in the least degree interrupted 

 by outlying tubercles, as is seen in the Hippopotamine or 

 ' Stenocoronine ' type. Sir Proby Cautley and myself have 

 thought we could distinguish four species of Stegodon, namely 

 E. (Steg.) Gliftii, E. (Steg.) bombifrons, E. (Steg.) insignis, and 

 E. (Steg.) Ganesa ? The first, besides other distinctive marks, 

 is at once characterized by the broad distinction of the ante- 

 penultimate and penultimate true molars being six-ridged, or 

 hexalophodont in number, the last true molar conformably 

 presenting an additional ridge and ' talon.' The first of the 

 ' intermediate series,' namely the last milk molar, has not 

 yet been observed entire in situ in the jaw, but I am prepared 

 to expect that, when determined, it will present five or six 

 ridges. This species, the remains of which were discovered 

 by Mr. Crawford in Ava, constitutes the passage into the 

 Mastodons ; this is indicated both by the limited (i.e. senary) 

 number of ridges, and by the circumstance that the crowns 

 of the molars exhibit a very obsolete or indistinct trace of a 

 longitudinal bipartient cleft, as in the Mastodons. Further, 

 in the only well-preserved palate-specimen at present known, 

 the outer side of the upper molars is higher, and the inner 

 side lower and more worn, being another point of agreement 

 with the Mastodontoid rather than with the Elephantoid type. 

 Where nearly allied groups inosculate, the intermediate 



1 It has been suggested to mo that the 

 contrasted terms of Dinotherian and 

 Hippopotamine types may mislead, 

 through being supposed to imply a 

 greater amount both of affinity and of 



difference than is intended. I propose 

 therefore to substitute for the former 

 ' Eurycoronine ' or broad-crowned type, 

 and for the latter 'Stenocoronine' or 

 narrow-crowned type. 



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