CHAP, xxxiii.] PHYSICAL GEOGRAPHY. 291 



Aru, do not extend into Ceram, indicating with a force 

 which every naturalist will appreciate, that the two latter 

 countries have received their faunas in a radically different 

 manner. Again, a true kangaroo is found in Aru, and the 

 same species occurs in Mysol, which is equally Papuan in 

 its productions, while either the same, or one closely allied 

 to it, inhabits New Guinea ; but no such animal is found 

 in Ceram, which is only sixty miles from Mysol. Another 

 small marsupial animal (Perameles doreyanus) is common 

 to Aru and New Guinea. The insects show exactly the 

 same results. The butterflies of Aru are all either New 

 Guinea species, or very slightly modified forms ; whereas 

 those of Ceram are more distinct than are the birds of the 

 two countries. 



It is now generally admitted that we may safely reason 

 on such facts as these, which supply a link in the defective 

 geological record. The upward and downward movements 

 which any country has undergone, and the succession of 

 such movements, can be determined with much accuracy ; 

 but geology alone can tell us nothing of lands which have 

 entirely disappeared beneath the ocean. Here physical 

 geography and the distribution of animals and plants are 

 of the greatest service. By ascertaining the depth of the 

 seas separating one country from another, we can form 

 some judgment of the changes which are taking place. If 

 there are other evidences of subsidence, a shallow sea 



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