Apes. 34 f 



" the Protamniota split up into two stems, one 

 that of the Mammalia, the other common to 

 Reptilia and Aves" 1 And they are " proved " 

 to have exjsted ( although no one knows what 

 they were like ) because they were the neces- 

 sary precursors of 



(16), The Pro-mammalia, the earliest pro- 

 genitors of all the Mammalia. And these were 

 followed by (17,) Marsupialia, or Kangaroos. 

 " But," says Prof. Huxley, " the existing Opos- 

 sums and Kangaroos are certainly extremely 

 modified and remote from their ancestors the 

 ' Prodidelphiaj of which we have not, at pre- 

 sent, the slightest knowledge. The mode of 

 origin of the Monodelphia from these is a. very 

 difficult problem, for the most part left open 

 by Professor Haeckel." 8 Observe : Of these 

 Prodidelphia " we have not, at present, the 

 slightest knowledge." And yet this knowledge 

 we " certainly " have : First, that they are the 

 " ancestors " of " the existing Opossums and 

 Kangaroos " ; and Second, that these Opossums 

 and Kangaroos " are certainly extremely modi- 

 fied and remote from their ancestors the Prodi- 

 ddphia" No wonder that " the mode of origin 

 of the Monodelphia from these is a very difficult 



1 " Critiques and Addresses," p. 317. 

 * Ibid., p. 318. 



