14 Original Articles. [Jan., 



Mammalian life in existence upon our planet. During the ages which 

 followed, the higher orders of the Mammalian series became developed 

 in the great Paleogean Continent, while, for reasons which at present 

 we cannot explain, Marsupialism remained permanent in Australia, 

 and a varied series of herbivorous, insectivorous, and carnivorous 

 Mammals, all united by the common link of this mode of reproduction, 

 were developed in this isolated region. In comparatively recent times 

 the water-strait between Australia and Asia again became narrowed, 

 and placental forms of Mammals have thus penetrated into the former 

 land of Marsupials. 



It has thus, as I believe, come to pass that in Australia we find the 

 Mammalian Fauna composed of two elements — the implacental and 

 the placental ; the Mammals of the former type being the old indi- 

 genous denizens of the country ; the latter to be regarded as probably 

 nothing more than intruders of comparatively recent introduction. 

 Let us first consider the former and more characteristic portion of the 

 Australian Mammal-fauna. 



Beginning with the lowest Implacentals, we first meet at the outset 

 with two forms of life so very different from the rest of their 

 kindred, that they are now universally allowed to rank as a separate 

 order, and by some of our most eminent authorities even as a distinct 

 sub-class of the Mammalia. These are the extraordinary genera Orni- 

 thorhynchus and Echidna, which in their toothless jaws, in the confor- 

 mation of the sternum and scapula, and especially in the structure 

 of their reproductive organs, exhibit such unmistakable signs of 

 divergence towards the class of birds, as to have acquired the name of 

 Omithodelphia. The Ornithorhynchus inhabits the South-eastern por- 

 tion of the Australian continent and Tasmania. Of the genus Echidna 

 two species are commonly recognized — E. hystrix of the southern parts 

 of Australia, and E. setosa of Tasmania. These three animals are the 

 sole existing representatives of the class Monotremata, and would of 

 themselves be sufficient, even were all other signs absent, to stamp 

 the region that they inhabit as a land of zoological marvels. 



The second order of Implacental Mammals, although not abso- 

 lutely restricted to Australia, since one distinct branch of it is purely 

 American, constitutes perhaps a still more characteristic feature of its 

 Fauna than even the Monotremes. At all events the Marsupials are 

 so abundant in genera and species as to form by far the most preva- 

 lent portion of the Australian Mammal-fauna. While all the classes 

 of Placental Mammals represented in Australia only furnish about 

 53 species belonging to 11 genera, upwards of 100 distinct species of 

 Marsupials appertaining to 16 generic forms are already registered in 

 our catalogues, and there is no doubt that in the little known dis- 

 tricts of the north and west, others still await the researches of future 

 explorers. Following the views of Mr. Waterhouse, I divide the 

 Australian Marsupials into five families : the Macropodida), or Kan- 

 garoos: the Phascolomyida?, or Wombats; the Phalangistidas, or 

 Phalangers ; the Peramelidaa, or Bandicoots ; and the Dasyuridaa, or 

 Dasyures. 



The Kangaroos or Macropodidas must be considered as par ex- 



