60 



INTRODUCTION. 



opposable thumb of primary importance, places the 

 Opossums and Phalangers in the same group with 

 the Quadrumana and Bimana, giving to the group 

 the name of Cheiropoda, and dividing it as follows : 



The arrangement adopted in this work, and that 

 which I originally published, in 1838, in the Cata- 

 logue of the Mammalia preserved in the Museum of 

 the Zoological Society, is as follows : 



Families. Genera. 



DIDELPHIDJE. . Didelphvs. 



{Thylacinus. 

 Dasyurus. 

 Phascogale. 

 MYRMECOBIID^E. Myrmecobius. 



Sub-genera 

 Cheironectes. 



t Phascolarctus, 

 PHASCOLOMYID^:. Phascolomys. 



( Kchidna. 



VMoNOTREMATA. ^ Ornithorhyn- 

 (. chua. 



