GIANT TORTOISES AND THEIR 

 DISTRIBUTION 



By R. LYDEKKER 



From their abnormal bodily size, their restriction at the present 

 day to two widely sundered groups of tropical islands, the 

 number of species and the hosts of individuals by which they 

 were represented a couple of centuries ago, the extent to 

 which living specimens were carried by the old navigators 

 to islands other than their own, the complete or impending 

 extermination or extinction of many of the species and the 

 great age to which they live, the land-tortoises commonly 

 distinguished by the prefix " giant " have very naturally 

 attracted, both on the part of naturalists and of the general 

 public, an amount of interest and attention far in excess of that 

 accorded to any of their smaller continental cousins. The 

 interest attaching to these huge and heavily armoured reptiles 

 is, however, by no means confined to the points indicated 

 above. On the contrary, their study leads to questions of far 

 wider and more important scope, such as the origin of races 

 and species, the means by which island animals have reached 

 their present habitats, and the division of islands into those of 

 "oceanic" and those of "continental" origin. Nor is this all, 

 for in Tertiary times, from the Lower Pliocene to the Eocene, 

 giant tortoises, in place of being confined to one group of 

 islands in the Indian Ocean and a second in the South Pacific, 

 were distributed over all the great continents of the world, thus 

 giving rise to the inquiry why they disappeared from the latter 

 to survive in the former areas. 



As a matter of fact, however, the term " giant tortoises " is 

 a relative one, scarcely capable of very precise definition ; for 

 as regards bodily size one living African species, Testudo 

 calcarata, approaches the smaller island forms ; what is more 

 important it agrees very closely in the form of the forepart 

 of the lower half of the shell, or plastron, which is produced 

 into a pair of horn-like processes, with the huge extinct tortoise 



302 



