GIANT TORTOISES AND THEIR DISTRIBUTION 305 



and all the tortoises eventually disappeared from the three 

 Mascarene Islands. The Reunion species was the first to 

 vanish, so that even its identification was for a long time a 

 matter of difficulty ; but of the Rodriguez forms a few shells 

 are preserved, and there is the above-mentioned Paris example 

 of the great Testudo indica of Mauritius. 



That species, together with certain other less-well-known 

 tortoises from the same island and Vosmaer's tortoise {T. 

 vosmaeri) of Rodriguez, is distinguished by two specialised 

 features of the horny plates on the front margin of the 

 shell from all the other members of the giant group. Thus 

 in the upper shell, or carapace, the small unpaired plate 

 technically known as the nuchal shield, which is present in 

 so many tortoises immediately above the neck, is completely 

 absent, thereby permitting the first pair of large marginal 

 shields to come into contact in the middle line. Similarly, 

 the paired gular shields which in most tortoises cover the 

 front point of the lower shell, or plastron, have coalesced 

 into a single shield. Vosmaer's tortoise, which was first 

 described in 1792 on the evidence of a shell in the museum 

 at The Hague, is further peculiar on account of the extreme 

 tenuity and fragile nature of the bony framework of the 

 shell — a feature which has been attributed to scarcity of 

 calcareous material in its habitat but which may well be 

 due to the absence of need for protection against attack in 

 island animals. This tenuity of shell reappears in certain 

 Galapagos tortoises, all of which agree with the Mascarene 

 species in their flattened heads and the absence of a nuchal 

 shield to the upper shell, although they differ by the retention 

 of paired gulars. 



Of the Reunion tortoise, like those of the Comoro and 

 Amirante Islands, very little is known ; but it is noteworthy 

 that certain remains from the Mascarenes indicate species 

 with paired gular shields which were probably related to the 

 long extinct Siwalik tortoise of India, of which more anon. 



This, however, does not exhaust what I have to say in 

 regard to the Mascarene species; for in June 1895 the Hon. 

 Walter Rothschild received two living tortoises from the 

 Seychelles, the smaller of which proved to agree with the 

 Mascarene species in the absence of a nuchal shield, and 

 probably came from one of the smaller islands of that group. 



