III.] INDEPENDENT SIMILARITIES OF STRUCTURE. 77 



Indeed, the resemblance is so striking between some 

 orders of placental mammals and their marsupial analogues 

 as, on Darwinian principles, to suggest the probability of 

 genetic affinity ; and it even led Professor Huxley, in his 

 Hunterian Lectures in 1866, to promulgate the notion 

 that a vast and widely-diffused marsupial fauna may have 

 existed anteriorly to the development of the ordinary 

 placental, non-pouched beasts, and that the carnivorous, 

 insectivorous, and herbivorous placentals may have re- 

 spectively descended from the carnivorous, insectivorous, 

 and herbivorous marsupials. 



Amongst other points, Professor Huxley called attention 

 to the resemblance between the anterior molars of the pla- 



TEETH OF TJROTRICHUS AND PERAMELES. 



cental dog with those of the marsupial thylacine. These, 

 indeed, are strikingly similar, but there are better examples 

 still of this sort of coincidence. It has often, for instance, 

 been remarked that the insectivorous marsupials, e.g. 

 Pcrctmdes, wonderfully correspond, as to the form of 

 certain of the grinding teeth, with certain insectivorous 

 placentals, e.g. Urotrichus. 



Again, the saltatory insectivores of Africa (Macroscelides) 

 not only resemble the kangaroo family (Macropodidce) in 

 their jumping habits and long hind legs, but also in the 

 structure of their molar teeth, and even, as the author 



