840 PHYLUM CHORDATA : CLASS MAMMALIA 



the hallux is opposable. The tail is generally long, and often 

 prehensile. The stomach is simple ; the caecum small. The 

 pouch is generally absent, but the young are often carried on 

 the back of the mother, their tails coiled round hers. Dentition, 



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 4134" 



Examples. — The Virginian or crab-eating opossum (Didelphys 

 marsupialis), with a pouch ; the woolly opossum {D. lanigera) ; 

 the aquatic Yapock (Chironectes), which feeds on fish and 

 smaller water animal?. 



2. Family Dasyurida?. — Carnivorous or insectivorous Marsupials. The 



limbs have cla^ved digits, five in front, four or five behind. The 

 canines are generally large. The stomach is simple ; there is 

 no caecum. 



ILxamples. — The Tasmanian wolf (Thylacinus), of dog-like form, 



dentition ^^^' and the Dasvure (Dasyurus), civet-like, den- 

 3134 



tition "*-^"^, are specialised as carui\H)res. The members of the 

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genus Phascoi^ale are small and insectivorous. The banded 



ant-eater (Myrmecnhius) of W. and S. Australia, a somewhat 



squirrel-like animal, has a long thread-like protrusible tongue, 



and more teeth than any other Marsupial, ^^^^-^^. It difters 



-' 3135 or 6 



markedly from the other members of the family. 



3. Family Notoryctidai. — This family has been erected for the mole- 



like Marsupial [Notoryctes typhlops) found in the sandy deserts 

 of S. Australia. It lives underground, is a rapid burrower, and 

 in its rudimentary eyes, keeled sternum, and some other respects, 

 markedly resembles the Cape golden mole. It is thus a good 

 illustration of " convergence," i.e. the appearance of similar 

 characters in forms not nearly related, apparently in indirect 

 response to similar conditions of life. 



4. Family Peramelida'. — The burrowing bandicoots, all small in size, 



insectivorous or omnivorous in diet. In the fore-feet two or 

 three of the middle toes are well developed and clawed, the 

 others being rudimentary ; in the hind-feet the hallux is small or 

 absent, the second and third toes are very slender and united 

 in the same fold of skin, the fourth toe is very Karge, the fifth 

 smaller — the whole foot suggesting that of the kangaroo. The 

 stomach is simple ; the caecum not large. Clavicles are absent 



in the adult but present in the foetus. Dentition. ^^^|^^. 



Examples. — The true bandicoot {Perameles), remarkable for its 

 allantoic placenta ; the native rabbit {Peragale lagotis) ; the 

 rat -like Chceropus. 



