DISTRIBUTION OF ORDERS. 33 



furnished by the Monotremata, comprising the two families of 

 duck-bills and echidnas, both restricted to Australia and the Isl- 

 and of Tasmania, and the Hyracoidea, an order consisting of two 

 genera, Hyrax (the coney) and Dendrohyrax, and about a dozen 

 species, all of which are restricted to the continent of Africa and 

 the immediately adjoining parts of Asia (Syria). The only orders 

 of terrestrial mammals which can lay claim to being cosmopolitan 

 are the Cheiroptera (bats) and Rodentia, none of the other orders, 

 except the Marsupialia unless the dingo, as a member of the Car- 

 nivora, be considered indigenous to the continent it now inhabits 

 having any representatives in Australia. Among birds we have 

 no instance of an order being restricted to the limits of a single con- 

 tinent. Among reptiles the Crocodilia are almost entirely confined 

 to the tropical and sub-tropical regions, and occur in both the East- 

 ern and Western Hemispheres. The Ophidia (serpents) have what 

 might be called a world-wide extension, although no member of 

 the order has been met with farther to the north than the Arctic 

 Circle. The order Anura (frogs and toads) among amphibians is 

 very nearly cosmopolitan ; the Urodela, on the other hand, com- 

 prising the tailed forms, such as the newts, salamanders, &c., are 

 almost strictly confined to the Northern Hemisphere, a few only of 

 its representatives passing through Central America as far south as 

 Colombia. The entire class of the Amphibia (as indigenous forms) 

 is absent from the vast majority of oceanic islands New Zealand, 

 New Caledonia, and the Andaman Islands, and possibly the Solo- 

 mon and Seychelles groups, almost alone, according to Darwin, 

 presenting exceptional instances. 



The marsupials afford a remarkable example of a comparatively 

 large order of animals occupying widely separated and discon- 

 tinuous areas. With the exception of the opossums, of which 

 there are two genera and about twenty species, confined to the 

 two continents of America, and more particularly to the tropi- 

 cal regions of these continents, all the members of this peculiar 

 and lowly-organized order of animals are strictly limited in their 

 range to the Australian continent and its dependent islands, and 

 some of the islands of the Malay Archipelago. In all the broad 

 intervening region Europe, Africa, and Asia no representative of 

 the order is to be met with. The Edentata ant-eaters, armadillos, 

 &c. are largely confined to the tropical and sub-tropical regions 



D 



