THE TEETH OF MARSUPIALIA. 



431 



and four true molars behind it, would not lead an observer 

 to suspect its real nature. 



No existing creature serves to connect the Kangaroos 

 closely with the wombat, but the extinct Diprotodon appears 

 to have in a measure bridged across the gap. 



The Wombats (Phascolomys) are heavily-built, inoffensive 

 creatures, which burrow in the ground and subsist largely 

 upon roots. In their dentition they closely simulate the 



Fro. 191 ('). 



Rodents, as they possess but a single pair of chisel-edged 

 incisors in either jaw, growing from persistent pulps, and 

 embedded in very deep and curved sockets. These differ from 

 the corresponding " dentes scalprarii " of true Rodents in that 

 there is a complete investment of cement, which passes over 

 the enamel in front of the tooth as well as covering its back 

 and sides. They are unlike the teeth of other Marsupials 

 in their structure, as the dentinal tubes do not penetrate 

 the enamel, which is therefore, probably, harder and denser 

 and so less readily worn away. 



The molar teeth also grow from persistent pulps, and 



