154 THE LIVING ANIMALS OF THE WORLD 



Hu 



these limbs take the form of flattened paddles, and in no 

 instance are more than two of the toes provided with claws. 

 The TORTOISKS are sub-divided by zoologists into 

 some six or eight subordinate groups or families, for 

 the most part distinguished by the respective modifi- 

 cations of their protective shells. This shell in all 

 tortoises and turtles consists of two essential elements 

 the upper or back casing, known as the " carapace," 

 and the under one, or so-called " plastron," which 

 covers the ventral surface. In some forms these two 

 elements are completely welded into one another, forming 

 a continuous box-like shell ; in others they are more or 

 less separate; while in yet another scries the lower 

 shell is rudimentary. These distinctions have been 

 found to constitute a convenient basis for classification. 



In the TRUE LAND-TORTOISES, which invite first 

 attention, the upper and lower shells are completely 

 united in a box-like form, and the neck, bent in tin. 

 form of the letter S, can be completely retracted within 

 it. The limbs are club-shaped, covered with horny 

 scales or tubercles, and adapted for walking, tin- 

 being unwebbed, and provided with strong claw-like nails. 

 Pre-eminent among this typical terrestrial scries 

 come the huge GIANT or ELEPHANT-TORTOISES, formerly 

 abundant, as their fossil remains indicate, in Southern 

 Europe, India, and North and South America, and now 

 represented only in the isolated oceanic islands of Aldabra, 

 <>tt Madagascar, the Seychelles, and the Galapagos groups. 

 Even within historic times they were very abundant in 



the islands of Mauritius and Rodrigues; but their huge size and lethargic habits, combined 



with their esculent qualities, have brought bout their extermination. Those remaining in 



the islands mentioned are now so reduced in numbers that there is a possibility of their 



becoming extinct at an early date, and this notwithstanding the strenuous endeavours that 



are being made to save them. A large percentage of 



the small residue of these giant Chelonians have been 



transported from their island homes and presented to the 



London Zoological Gardens, where they are now comfortably 



housed. 



An instructive idea of the aspect and relative dimen- 



sions of these giant tortoises may be obtained by a refer- 



ence to page vii of the First Volume, in which one of 



these Chelonians is shown to be equal in size and strength 



to carrying a human rider. It is recorded that these 



reptiles were so abundant in the island of Rodrigues in 



1691 that one might count as many as 3.000 of them in 



a single flock, and walk for over 100 paces upon their 



backs. All of these giant .tortoises, as obtained from 



separate island groups, or islets of the groups, exhibit 



characteristic differences, indicating the length of time 



they have been separated from one another. The 



age to which these giant tortois, , attain is altogether 



phenomenal. One example at Port Louis, Mauritius, 



ASIATIC TORTOISES 



A tortoi$f 9 like a turtle^ turned cvtr on itt back, 

 represents one tf the most kelplest of living animals 



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KURoi'KAN TORTOI 

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