424 A MANUAL OF DENTAL ANATOMY. 



My father, some years ago, described and figured the teeth 

 of a large number of Marsupial genera (" Philos. Transac.," 

 1850), and found that although in the different families the 

 tube system of the enamel varied in its richness and in the 

 depth to which the tubes penetrated, yet it was con- 

 spicuously present in the whole class, with the sole exception 

 of the Wombats, in whom nothing of the kind is to be found. 

 Prof. Moseley's specimens have afforded to me the opportu- 

 nity of study ing the development of this tubular enamel, and 

 the result of my investigations will be detailed elsewhere ; 

 but it may be mentioned that the formation of the enamel 

 tube appears to be precisely analogous to that of a dentine 

 tube, and at a certain period the enamel cells have appended 

 to them long processes like the dentinal fibres. The dila- 

 tation noticeable at the boundary line of the enamel and 

 the dentine (see Fig. 186) is a kind of clumsy joint brought 

 about by the coalescence at this point of the tube-forming cells 

 on the one side odontoblasts, on the other enamel cells. 



There exists one genus of flesh-eating marsupials whose 

 ferocity is such as to have gained for them the names of 

 wolf and tiger, while the resemblance of the head to that of 

 a dog has given origin to the popular name of " dog-headed 

 opossums." (*) 



The resemblance to the dog is in dentition even more 

 close than in external form : whilst retaining certain mar- 

 supial attributes, the teeth of the Thylacine are, so far as 

 their working capabilities go, almost exactly like those of the 

 dog. The dental formula is 



.4 1 3 4 

 1 3 1 P 3 m 4 



The incisors are small, close set, and sharp edged, the 



( ! ) It has of course no real relationship to the true opossums, which are 

 not found in Australia. 



