LIFE OF FLOWER in 



marsupials on which to work than was available to 

 Owen), was enabled to show that in the Marsupialia 

 only one pair of teeth in each jaw, at most, is preceded 

 by a milk-tooth. The tooth, in question, is the fifth 

 from the posterior end of the series, and whereas in the 

 adult animal it differs in character from those behind it, 

 its deciduous predecessor resembles the latter. The 

 replacing tooth was further considered to correspond 

 with the fourth or last premolar of placental mammals, 

 while the replaced tooth was regarded as the only one 

 in the entire series corresponding to the milk-teeth of 

 placental mammals. This view rendered it necessary, 

 of course, to regard all the four pairs of cheek-teeth 

 behind this abnormal one as corresponding to the true 

 molars of placentals, as had been done by Owen, thus 

 making, as already mentioned, marsupials to differ from 

 ordinary placentals by possessing four instead of three 

 pairs of these teeth. 



Before proceeding to notice an amendment which has 

 been proposed in regard to the homology of the one 

 successional tooth of the marsupials, certain other 

 features connected with it and its predecessor discussed 

 by Flower may be briefly mentioned. He noticed, to 

 quote from an admirable epitome of his observations on 

 this point, drawn up by Professor M'Intosh in the Scottish 

 Review for 1900, " that there were considerable differ- 

 ences in the various genera as to the relative period of 

 the animal's life at which the fall of the temporary molar 

 and the evolution of its successor takes place. In some, 

 as in the rat-kangaroos, it is one of the latest, the 

 temporary tooth retaining its place and its functions 

 until the animal has nearly, if not quite, reached its full 



