FOSSIL MARSUPIALS. 225 



Phascogales, Dasyures ; and, in common with South Australia, a Chceropus, whilst the genus Tarsipes 

 is peculiar to it. The Wombat is found in Van Diemen's Land and some of the islands in Bass 

 Strait. It is found in the south and east of the mainland of Australia, but not to the west and north. 

 Mr. Waterhouse notices that the Marsupials of the eastern districts are for the most part distinct from 

 those of the opposite side of the continent, there being, when his great work, which has been so 

 constantly referred to in this description, was written, but eight species out of upwards of sixty 

 inhabiting the two provinces. South Australia is the habitat of more common species than else- 

 where. The northern part of Australia has more species peculiar to it than the other divisions, 

 and some of its Dasynridee especially, and species of Cuscus also, are found in the Arm and other 

 islands to the north. The metropolis of the sub-genus Cuscus is in the Moluccas, where two species are 

 widely distributed, or one is restricted to certain islands. 



The other divisions of the genus are i-epresented by the Vulpine Phalanger, an animal with long loose 

 fur, which inhabits New South Wales, Western Australia, and North Australia ; by Cook's Phalanger, of 

 New South Wales and Van Diemen's Land. The genus Perameles, the Bandicoots, has species in 

 Van Diemen's Land, Australia, New Guinea, and in the Arm Islands, and the genus Petaurus has a 

 corresponding distribution. The Didelphidse are found in the United States, California, Mexico, Peru, 

 Guiana, Brazil, Paraguay, Banda Oriental, and Chili ; and Brazil is the country where they abound 

 the most in species and individuals, the number diminishing to the north and south. 



The Marsupials have a great ancestry, and some of them lived when the continents and oceans 

 of the earth were in very different relative positions to those they now occupy. Indeed, it is most 

 probable that the fossil remains of the most ancient mammal belong to this order. There is a small 

 double-fanged molar tooth of a mammal which was found by Plieninger, in 1847, contained in a jumble of 

 shells and of the remains of reptiles and fishes in strata beneath the Lias formation of Diegerloch, near 

 Stuttgart. It and another which was discovered close by, by the same professor, belonged to animals 

 which were dead when this topmost stratum of the Trias, immediately beneath the Lias, was being formed. 

 They are Triassic in age, therefore, and they somewhat resemble the back teeth of a fossil which was 

 found subsequently in the Purbeck strata of England, and which evidently belonged to a Marsupial more 

 or less resembling the existing Kangaroo-Rats or Potoroos, of the genus Hypsiprymnus. Later 

 on, Professor W. Boyd Dawkins, F.R.S., discovered a small tooth belonging to the same extinct genus 

 as that which included Plieninger's fossil, namely, Microlestes ; and its resemblance to one of Hypsi- 

 prymnus is even greater. Its position was high up in the Trias of Watchet in Somersetshire. Mr. Charles 

 Moore, of Bath, had previously found many specimens of teeth of the same family in a fissure, down 

 which they had been washed by the Triassic sea. 



A lower jaw of a small Mammal was found in the Trias of North America by Emmons ; and it 

 has on one side three incisors, one long canine, then a diastema, three premolars, and seven molars 

 with three points. It is therefore one of the Myrmecobius group. 



After the age of the Trias, when there was much continuous land surface, Europe was broken up 

 into a coral island tract, during the age of the collection of the Jurassic deposits. The islands were 

 tenanted by many small Marsupials, four species of which have been discovered in the deposits of 

 Stonesfield slate at the bottom of the Great Oolite. They belong to the extinct genera Amphithe- 

 rium, Phascolotherium, and Stereognathus, and the first somewhat resembled the Myrmecobius of 

 recent times ; but all that can be said is that they belonged to Marsupial animals. Piled on the Stones- 

 field slates are many hundred feet of strata, and high up amongst them, in the Swanage and Purbeck 

 districts, are deposits in which Messrs. Brodie and Beckles have found portions of the skeletons of 

 numerous insectivorous Marsupials, of which the genera Spalacotherium, Plagiaulax, Triconodon, and 

 Galestes are the most important. They were small, as a ride, and there has been much debate regard- 

 ing their affinities with modern insectivorous forms, and they are still surrounded with doubt. 



The appearance of the Mammalia without pouches took place in the Eocene age, and in the Old 

 and New World, and contemporaneously with them lived in France a kind of Opossum, some of whose 

 bones were found in the strata of Montmartre, near Paris ; and in later Tertiary strata other relics 

 have been found. These are the only instances of a fossil Didelphid occurring out of the New World ; 

 and there, where the Opossums are now characteristic animals, they were present in the last geological 

 age, for in the Brazilian. latest deposits remains of several species of Didelphys have been found. 



