chap, xi.] THE ETHIOPIAN REGION. 289 



reached the country ; and it was in consequence of this total 

 exemption from danger, that several groups of birds altogether 

 incapable of flight became developed here, culminating in the 

 huge and unwieldy Dodo, and the more active Aphanapteryx. 

 To the same cause may be attributed the development, in these 

 islands, of gigantic land-tortoises, far surpassing any others now 

 living on the globe. They appear to have formerly inhabited 

 Mauritius, Bourbon, and Rodriguez, and perhaps all the 

 other Mascarene islands, but having been recklessly destroyed, 

 now only survive in the small uninhabited Aldabra islands 

 north of the Seychelle group. The largest living specimen 

 (5^ feet long) is now in our Zoological Gardens. The only 

 other place where equally large tortoises (of an allied species) 

 are found, is the Galapagos islands, where they were equally free 

 from enemies till civilized man came upon the scene ; who, partly 

 by using them for food, partly by the introduction of pigs, which 

 destroy the eggs, has greatly diminished their numbers and 

 size, and will probably soon wholly exterminate them. It is a 

 curious fact, ascertained by Dr. Gunther, that the tortoises of 

 the Galapagos are more nearly related to the extinct tortoises of 

 Mauritius than is the living tortoise of Aldabra. This would 

 imply that several distinct groups or sub-genera of Testudo have 

 had a wide range over the globe, and that some of each have 

 survived in very distant localities. This is rendered quite con- 

 ceivable by the known antiquity of the genus Testudo, which 

 dates back to at least the Eocene formation (in North America) 

 with very little change of form. These sluggish reptiles, so 

 long-lived and so tenacious of life, may have remained un- 

 changed, while every higher animal type around them has 

 become extinct and been replaced by very different forms ; as 

 in the case of the living Emys tectum,, which is the sole survivor 

 of the strange Siwalik fauna of the Miocene epoch. The ascer- 

 tained history of the genus and the group, thus affords a satis- 

 factory explanation of the close affinity of the gigantic tortoises 

 of Mauritius and the Galapagos. 



The great island of Madagascar seems to have remained longer 

 united with Africa, till some of the smaller and more active 



