1874.] Dr. A. Giinther on Gigantic Land-Tortoises. 421 



We do not overlook the possibility that the alteration in secretion may 

 be partly due to the direct action of the drug on the secreting elements 

 of the kidneys, and we are still engaged in experiments on this subject. 



XL " Description of the Living and Extinct Races of Gigantic 

 Land-Tortoises. Parts I. and II. Introduction, and the Tor- 

 toises of the Galapagos Islands/' By Dr. ALBERT GUNTHER, 

 F.R.S. Received June 4, 1874. 



(Abstract.) 



The author having had the opportunity of examining a considerable 

 collection of the remains of Tortoises found in the islands of Mauritius 

 and Rodriguez associated with the bones of the Dodo and Solitaire, has 

 arrived at the following conclusions : 



1. These remains clearly indicate the former existence of several 

 species of gigantic Land-Tortoises, the Rodriguez species differing more 

 markedly from those of the Mauritius than these latter among them- 

 selves. All these species appear to have become extinct in modern 

 times. 



2. These extinct Tortoises of the Mascarenes are distinguished by a 

 flat cranium, truncated beak, and a broad bridge between the foramina 

 obturatoria. 



3. All the other examples of gigantic Tortoises preserved in our mu- 

 seums, and said to have been brought from the Mascarenes, and likewise 

 the single species which is known still to survive, in a wild state, in the 

 small island of Aldabra, have a convex cranium, truncated beak, and a 

 narrow bridge between the obturator foramina ; and therefore are 

 specifically, if not generic-ally, distinct from the extinct ones. 



4. On the other hand, there exists the greatest affinity between those 

 contemporaries of the Dodo and Solitaire and the Tortoises still inhabit- 

 ing the Galapagos archipelago. 



These unexpected results induced the author to subject to a detailed 

 examination all the available material of the gigantic Tortoises from the 

 Mascarenes and Galapagos which are still living, or were believed to be 

 living, and are commonly called Testudo indica and Testudo elepliantopus, 

 and to collect all the historical evidence referring to them. Thus, in the 

 first (introductory} part of the paper a selection from the accounts of tra- 

 vellers is given, by which it is clearly shown that the presence of these 

 Tortoises at two so distant stations as the Galapagos and Mascarenes 

 cannot be accounted for by the agency of man, at least not in historical 

 times, and therefore that these animals must be regarded as indi- 

 genous. 



The second part consists of a description of the Galapagos Tortoises. 

 The author shows that the opinion of some of the older travellers, viz. 



