MAMMALIA. 25 



States, Europe and India. Mastodons preceded the Elephants. They are 

 distinguished from the Elephants by their less complex molars; flatter cranium ; 

 smaller development of the frontal air-cells, presenting a less intelligent ap- 

 pearance; more elongated body, but not much, if any, higher; and limbs 

 proportionately shorter and stronger. The surface of the teeth, instead of 

 being cleft into numerous thin plates, was divided into wedge shaped trans- 

 verse ridges, and the summit of these were subdivided into small cones, more 



or less resembling nipples, whence the name. When worn, the protuberances 

 became truncated into a lozenge form. Bronn and Owen state that the Mas- 

 todon is, characterized by lower incisors (tusks), and by molars which are re- 

 placed from back to front, excepting one or more milk-molars; while in the 

 Elephant there are no inferior incisors, and all the molars are replaced in a 

 horizontal direction. Falconer shows that these generic distinctions are neither 

 absolute nor constant. He makes the Mastodons include all the elephantoid 

 species which have the crowns of the molars comparatively simple and uni- 

 formly divided into two subequal divisions by a longitudinal cleft; the ridges 

 limited to three or four in number, and invariably more or less concave across; 

 the enamel thick (in some specimens three times as thick as in the Mammoth), 

 and in conical or compressed points; and the valleys between the ridges deep 

 and empty, or with but a sparing quantity of cement. The Elephants, on the 

 other hand, include all the proboscidians which have the crowns of the molars 

 more complex, and usually wanting in a longitudinal line of division; the 

 ridges more numerous and less definite, each being composed of a greater 

 number of mammillary points, which ai'e most elevated in the middle, ren 



