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

chap, viii.] TERTIARY REPTILES. 1G5gives support to the theory of a great eastward extension ofAustralia in Tertiary times.Extinct Teetiaey Eepttles.These will not occupy us long, as no very great number areknown, and most of them belong to a few principal forms ofcomparatively little geographical interest.Tortoises are perhaps the most abundant of the Tertiaryreptiles. They are numerous in the Eocene and Mioceneformations both in Europe and North America. The 'generaEmys and Trionyx abound in both countries, as well as in theMiocene of India. Land tortoises occur in the Eocene of NorthAmerica and in the Miocene of Europe and India, where thehuge Colossochelys, twelve feet long, has been found. In thePliocene deposits of Switzerland the living American genusChelydra has been met with. These facts, together with theoccurrence of a living species in the Miocene of India, showthat this order of reptiles is of great antiquity, and that mostof the genera once had a wider range than now.Crocodiles, allied to the three forms now characteristic ofIndia, Africa, and America, have been found in the Eocene ofour own country, and several species of Crocodihis have occurredin beds of the same age in North America.Lizards are very ancient, many small terrestrial formsoccurring in all the Tertiary deposits. A species of the genusChamceleo is recorded from the Eocene of North America, togetherwith several extinct genera.Snakes were well developed in the Eocene period, whereremains of several have been found which must have been fromtwelve to twenty feet long. An extinct species of true viper hasoccurred in the Miocene of France, and one of the Pythonideein the Miocene brown coal of Germany.Batrachia occur but sparingly in a fossil state in the Tertiarydeposits. The most remarkable is the large Salamander{Andreas) from the Upper Miocene of Switzerland, which