xnr DISTRIBUTION 609 



Lucas on the west and the Rio Grande del Norte on the east, 

 separates it from the Neotropical region. 



The Nearctic differs from the Palsearctic region in the possession 

 of several characteristic Mammals, such as Opossums (Didelphyidce), 

 the Skunk, Racoon, &c. ; many Birds, such as the Blue-jays, 

 and Turkey-buzzards, &c. ; Reptiles, such as Rattlesnakes and 

 Iguanas ; Amphibians, including the Axolotl, Necturus, Siren, and 

 other large Urodeles ; and numerous fresh- water Fishes, including 

 Amia, Lepidosteus, Polyodon, and Scaphirhynchus. Only three 

 entire families are endemic, two of Rodents, and one of Passerines. 



On the other hand, the resemblances between the two northern 

 regions are very close. Both possess Wild Cats, Hyaenas, Foxes, 

 Weasels, Bears, Elk, Deer, Wild Oxen, Beavers, Voles, Squirrels, 

 Marmots, and Hares, the species of the one region being all closely 

 allied to, and sometimes identical with, those of the other. Thrushes, 

 Wrens, Tits, and Finches are also common to the two regions, and, 

 generally speaking, the differences between them are, as we shall see, 

 nothing like so striking as those between either of them and the 

 region or regions bounding it to the south. Hence the Palaearctic 

 and Nearctic regions are sometimes grouped together as a single 

 Holarctic Region. 



In the southern regions the characteristic features are much 

 more striking. The Ethiopian Region is constituted by the 

 whole of Africa and Arabia south of the Tropic of Cancer, together 

 with Madagascar, Mauritius, Bourbon, Rodriguez, and the 

 Seychelles. The region is bounded by sea on the west, south, 

 and east, but on the north it is perfectly continuous with the 

 Palsearctic region, and it certainly seems a very remarkable fact, 

 until we remember what an impassable barrier is afforded by a 

 sandy desert of great extent, that there should be more difference 

 between the faunae of northern and central Africa than between 

 those of England and Japan, or of Alaska and Florida. 



Among the animals most characteristic of the Ethiopian region 

 and not found elsewhere are the Gorilla, the Chimpanzee, several 

 Baboons, and the large majority of Lemurs, including the curious 

 Aye-aye (Chiromys) ; several peculiar Insectivora, such as the 

 Golden Moles (Chrysochloridce), and the River Shrew (Pota- 

 mogale) ; the African Elephant, the Hippopotamus, two or three 

 species of Rhinoceros, the Zebras and Quaggas, the Giraffe and 

 Okapi, and more than seventy species of Antelopes ; the 

 Aardvark (Orycteropus), one of the most singular types of 

 Edentata ; the Plantain-eaters (Musiphagidce), the Secretary 

 Bird (Serpentarius), and many other families and genera of 

 Birds ; numerous snakes and other Reptiles, and several fresh- 

 water Fishes, including the Dipnoan Protopterus, and the Ganoid 

 Polypterus. The Lion, Leopard, and Ostrich are also characteristic, 



