6;o 



MANUAL OF ZOOLOGY. 



rence ; but Opossums, closely allied to the existing American 

 forms, have been discovered in the Miocene and Eocene rocks 

 of Europe, and have been referred to a distinct genus under 

 the name of Peratherium. It is also interesting to note that 

 the Upper Jurassic beds have recently yielded to the researches 

 of Professor Marsh the first fossil Marsupials which have been 

 detected in the North American continent in beds older than 

 the Post-pliocene, and that these belong to an extinct type of 

 the at present exclusively American family of the Didelphidce. 



The next occurrence of Marsupials is in the later Tertiary 

 (Pliocene) and in the Post-tertiary epoch ; and here they are 

 represented by some very remarkable forms. The remains in 

 question have been found in the bone-caves of Australia the 

 country in which Marsupials now abound above every other part 

 of the globe ; and they show that Australia, at no distant geo- 

 logical period, possessed a Marsupial fauna, much resembling 

 that which it has at present, but of forms comparatively of a 

 much more gigantic size. In the remains from the Australian 

 bone-caves almost all the most characteristic living Marsupials 

 of Australia and Van Diemen's Land are represented ; but the 

 extinct forms are usually of much greater size. .We have 



Wombats, Phalangers, Flying 

 Phalangers, and Kangaroos, 

 with carnivorous Marsupials 

 resembling the recent Thyla- 

 dnns and Dasyurus. The two 

 most remarkable of these ex- 

 tinct forms are Diprotodon and 

 Thylacoleo. In most essential 

 respects Diprotodon resembled 

 the Kangaroos, the dentition, 

 especially, showing many points 

 of affinity. The hind-limbs, however, of Diprotodon were by 

 no means so disproportionately long as in the Kangaroos. In 

 size Diprotodon must have many times exceeded the largest of 

 the living Kangaroos, since the skull measures three feet in 

 length (fig. 371). The affinities of Thylacoleo are disputed. 

 The great feature in the dentition is the presence in either jaw 

 of one huge, compressed, and trenchant prsemolar. This is 

 regarded as corresponding to the great cutting prsemolar of 

 the Kangaroo-rats (Hypsiprymnus). Upon the whole, there- 

 fore, Professor Flower concludes that " Thylacoleo is a highly 

 modified and aberrant form of the type of Marsupials now 

 represented by the Macropodidce and Phalangistidce, though not 

 belonging to either of these families as now restricted," and 



Fig- 371. Skull of Diprotodon australis. 



