308 SCIENCE PROGRESS 



relatively short necks, combined with the presence of a nuchal 

 and paired gular shields to the shell. To define the special 

 characteristics of the two species from these islands would be 

 out of place on the present occasion ; but it may be mentioned 

 that the North Aldabra T. gigantea (also known as T. elephantina 

 and T. holoUssd) has a very thick and massive shell, which may 

 attain a length of 49 inches in a straight line and of 6\\ inches 

 over the curve. Of this species there are no examples now 

 surviving in a wild state on Aldabra, but there are (or were 

 recently) several living in the Seychelles, where they are kept 

 in a semi-domesticated condition by the planters, and there is 

 also a single well-known example in St, Helena ; whilst, as 

 mentioned above, the Matara tortoise in Ceylon may belong 

 to this species. A fine specimen was also received in 1893 

 by Mr. Rothschild and kept for several years, at any rate, 

 in the park and hothouses at Tring. 



Daudin's tortoise {Testiido daudini) of South Aldabra, on the 

 other hand, still survives in considerable numbers on its native 

 island. This tortoise, which has a thinner shell, of somewhat 

 peculiar shape, appears to be the largest existing member of the 

 whole group, the shell of a specimen in the possession of 

 Mr. Rothschild measuring 55 inches in a straight line. For 

 a long period — it is said about 150 years, although there is 

 some reason for doubting the accuracy of the statement — this 

 tortoise, which is a male, lived on Egmont Island, in the Chagos 

 group, lying to the south of the Maldives, whence it was carried 

 to Mauritius and ultimately in 1897 to Tring. South Aldabra, 

 which is a coral island and the largest of the group, is nowa- 

 days but little visited ; it is also very difficult to traverse, so that 

 it is no easy matter to see, let alone capture, the tortoises. 

 Nevertheless, seven were taken and despatched to Europe in 

 1895, six of which reached their destination. 



All the Aldabra tortoises present a curious structural 

 peculiarity by which they are distinguished from those of the 

 Mascarene and, with one exception, from those of the Galapagos 

 Islands. This peculiarity consists in the third vertebra of the 

 neck being biconvex, whereas in the other groups it is the 

 fourth vertebra which is biconvex. Curiously enough, however, 

 one of the Galapagos species, T. galapagocnsis, of Charles Island, 

 as pointed out by Dr. Gi'mther in the paper standing sixth on 

 the list, agrees in this respect with the Aldabra tortoises. Such 



