The geographical distribution of animals, with a study of the relations ...

;400 ZOOLOGICAL GEOGEAPHY. [part hi.no actual land connection is required for birds which can crossconsiderable arms of the sea.Eeptiles again seem to offer no more support to the view thando mammalia or birds. Among snakes there are no families incommon that have not a very wide distribution. Among lizardsthe Gymnopthalmidae are the only family that favour thenotion, since they are found in Australia and South America,but not in the Oriental region. Yet they occur in both thePalaBarctic and Ethiopian regions, and their distribution is altogethertoo erratic to be of any value in a case of this kindand the same remarks apply to the tortoises of the familyChelydidse.The Amphibia, however, furnishus with some more decidedfacts. We have first the family of tree-frogs, Pelodryade, confinedto the two regions ,Litoria, a genus of the family Hylidsepeculiar to Australia, but with one species in Paraguay ;and inthe family Discoglossidse, the Australian genus Chiroleptes hasits nearest ally in the Chilian genus Calyptocephalus.Fresh-water fishes give yet clearer evidence.Three groups areexclusively found in these two regions ;Aphritis, a fresh-watergenus of Trachinidse, has one species in Tasmania and twoothers in Patagonia ;the Haplochitonidre inhabit only Terra delFuego, the Falkland Islands and South Australia; while thegenus Galaxias (forming the family Galaxidse) is confined toSouth Temperate America, Australia, and New Zealand. Wehave also the genus Osteoglossum confined to the tropicalrivers of Eastern South America, the Indo-Malay Islands andAustralia.It is important here to notice that the heat-loving Eeptiliaafford hardly any indications of close affinity between the tworegions, while the cold-enduring amphibia and fresh-waterfish, offer them in abundance. Taking this fact in connectionwith the absence of all indications of close affinityamong the mammalia and terrestrial birds, the conclusion seemsinevitable that there has been no land-connection between thetwo regions within the period of existing species, genera, orfamilies. Yet some interchange of amphibia and fresh-water