410 



GEOGRAPHICAL ZOOLOGY. 



[PART iv. 



Remarks on the Distribution of the Chelonia. 



The four families into which the Chelonia are classed have 

 all of them a wide distribution, though none are universal. 

 The Ethiopian region seems to be the richest, as it possesses 3 

 of the four families, while no other region has more than 2 ; 

 and it also possesses 7 peculiar genera. _ Next comes the Neo- 

 tropical region with 2 families and j6 ' peculiar genera ; the 

 Australian with 3, and the Nearctic with 2 peculiar genera; 

 while the Oriental and Palsearctic regions possess none that 

 are peculiar. There are about 30 genera and 200 species 

 in the whole order. 



Fossil Chelonia. The earliest undoubted remains of this order 

 occur in the Upper Oolite. These belong to the Cheloniidse 

 and Emydidse, which are also found in the Chalk. In the 

 Tertiary beds Chelonia are more abundant, and the Trionychidse 

 now appear. The Testudinidse are first met with in the Miocene 

 formation of Europe and the Eocene of North America, the 

 most remarkable being the gigantic Colossochelys Atlas of the 

 Siwalik Hills. It appears, therefore, that the families of the 

 order Chelonia were already specialised in the Secondary period, 

 a fact which, together with their more or less aquatic habits, 

 sufficiently accounts for their generally wide distribution. 

 Species of Testudo, Emys, and Trionyx, are found in the Upper 

 Miocene of the south of France. 



