THE AUSTRALIAN MUSEU^r MAGAZINE. 



tals is entire, l)ut in 

 marsu})ials it is 

 pierced l)y two 

 opening's. And the 

 lower jaw in prac- 

 tically all niarsn- 

 pials {Tarsipes \< 

 the only exception ) 

 has a prononnced 

 inward l)end to the 

 lower 1)order. There 

 are many other 

 anatomical differ- 

 ences which distin- 

 guish marsupials 

 from placentals ; 

 thus in marsupials 

 the Ijrain is simpler 

 than, and not 



so wrinkled as that of higher mammals, 

 and there are marked differences in the 

 rei^roductive systems of the two groups. 

 Again, if we examine the spiny an- 

 teater of New Guinea, we find that it 

 has a long slender snout, a feeble lower 

 jaw and no teeth; it has a long protus- 

 ible tongue which it uses to lap up the 

 ants which form its staple diet. In 

 these particulars it strongly resembles 

 the great anteater or ant bear of South 

 America, bi;t in internal structure it is 



The Wombat has much in common with the Beaver. Both gnaw 



and dig and have evolved the same general form, but they are 



nevertheless descended from quite different ancestors. 



Plioto. — 'G. C. Clutton. 



HABITUS AND HERITAGE. 



When two animals belonging to dif- 

 ferent groups have acquired a similar 

 appearance because of their adaptation 

 to similar modes of life we say they 

 haAe the same habitus. And wlien we 

 find that they differ fundamentally in 

 structure, that their class characters are 

 unlike, and that the sum total of their 

 features necessitates their being placed 

 in different groups, we say that they 



wholly unlike that animal, and reveals differ in heritage. Thus the marsupial 

 its close relationship to the other mono- heritage is revealed by the presence of a 

 t^-eme, namely the platypus. i)ouch, by the perforated palate, by 



the other characters 

 common to marsu' 

 pials and not found 

 in otlier mammals. 

 Tiiese are the fea- 

 tui'es which indicate 

 the true relation- 

 ships of animals, 

 while the habitus 

 characters tend to 

 obscure the true re- 

 hitionsliips. Thus 



when Australian 



mammals were first 

 made known to the 

 world by Captain 

 Cook's voyages, tlie 

 naturalists of the 

 time were i^sled 

 by their sup«^cial 

 resemblance te^well- 



known animals, and 



The Beaver, being a water dweller has developed a large paddle- i.i l-o.irvo-..,->/^ f~,r. 



like tail. Plioto.— G. C. Clutton. ''"*' KangaiOO, lOr 



