252 GEOGRAPHICAL ZOOLOGY. [part iv. 



in form the flying squirrels of North America and India, but 

 often no larger than a mouse ; the beautiful dormouse-like 

 .Dromicice, one species of which is only 2^ inches long or less 

 than the harvest-mouse ; and the little Tarsipes, a true honey- 

 sucker with an extensile tongue, and of the size of a mouse. 

 These extreme modifications and specializations within the range 

 of a single family, are sufficient to indicate the great antiquity 

 of the Australian fauna ; and they render it almost certain that 

 the region it occupied was once much more extensive, so as 

 to supply the variety of conditions and the struggle between 

 competing forms of life, which would be required to develop so 

 many curiously modified forms, of which we now probably see 

 only a remnant. 



The Phalangistidse not only range over all Australia and 

 Tasmania, but over the whole of the Austro-Malayan sub-region 

 from New Guinea to the Moluccas and Celebes. The distribu- 

 tion of the genera is as follows : — Phascolarctos (1 sp.), the 

 koala, East Australia ; Phalangista (5 sp.), East, South, and West 

 Australia, and Tasmania ; Cuscus (8 sp.), woolly phalangers, 

 New Guinea, North Australia, Timor, Moluccas and Celebes ; 

 Petaurista (1 sp.) large flying phalanger, East Australia ; 

 Belideus (5 sp.), flying opossums, South, East, and North Aus- 

 tralia, New Guiana and Moluccas ; Acrobata (1 sp.), pigmy 

 flying opossum, South and East Australia; Dromicia (5 sp.), 

 dormouse-phalangers, West and East Australia, and Tasmania; 

 Tarsipes (1 sp.), West Australia. 



Thylacoleo, a large extinct marsupial of doubtful affinities, 

 seems to be somewhat intermediate between this family and the 

 kangaroos. Professor Owen considered it to be carnivorous, and 

 able to prey upon the huge Diprotodon, while Professor Flower 

 and Mr. Gerard Krefft, believe that it was herbivorous. 



Family 82.— PHASCOLOMYID^E. (1 Genus, 3 Species.) 



