3G0 



PROCEEDINGS OF THE ACADEMY OP 



[1886. 



in the molar series of the mammals of this period do not exist. 

 That is, the only distinction drawn between molars and premolars 

 is one of form ; we have no data as to permanent and deciduous 

 dentition, except possibly in the genus Triconodon. The rule 

 adopted is that, where the post-canine teeth are not all alike, the 

 series of like form following the canine are called premolars ; 

 and those behind these, of another form, are called molars. 

 This rule has been applied to all genera, excepting Phascolo- 

 therium and Diplocynodon, where all the post-canine teeth are 

 practically alike. 



DROMATHERITJM. 

 Dromatherium sylvestre Emmons. 



Generic Characters. Incisors and canines erect. Molars and 

 premolars unlike. Molar-premolar series compact, leaving a 

 wide diastema between the canine and first premolar. Premolars 



Dromatherium sylvestre Em. Magnified. 



high, styloid and procumbent, with no cingulum and probably 

 single fanged. Molars bifanged with high pointed crowns and 

 minute sometimes bifid cusps on the anterior slope and distinct 

 pointed cusps on the posterior slopes. The dental formula is 



Pm. 



M. 



The incisors are nearly erect, and are separated by interspaces 

 equaling the diameter of their crowns, which indicates that the 

 superior incisors interlocked with them. Ij is low and small ; Ij 

 is larger and more erect ; I3 is very high, slender and slightly 

 recurved, resembling the canine. The canine is tall, stout and 

 recurved, and in form is similar to the canine of Peralestes. 

 There is no indication of a double fang. A wide diastema sep- 

 arates this tooth from the premolars. These teeth are styloid 

 in ^hape, and strongly procumbent. The two anterior are appar- 



