312 Royal Society. 



wild state, in the small island of Aldabra, have a convex cranium, 

 trimeated beak, and a narrow bridge between the obturator 

 foramina ; and therefore are specifically, if not generically, distinct 

 from the extinct ones. 



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

 these contemporaries of the Dodo and Solitaire and the Tortoises 

 still inhabiting the Galapagos archipelago. 



These unexpected results induced the author to subject to a 

 detailed examination all the available material of the gigantic Tor- 

 toises from the Mascarenes and Galapagos which are still living, 

 or were beheved to be living, and are commonly called Testudo 

 indica and Testudo elejihantopus, 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 travellers 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 Tor- 

 toises. The author shows that the opinion of some of the older 

 travellers, viz. that the different islands of the group are inhabited 

 by different races, is perfectly correct ; and he distinguishes four 

 species, the adults of which are characterized as follows : — 



A. Shell broad, with more or less corrugated plates. STcull with 

 the palatal region concave ; outer pterygoid edge sharp in its entire 

 length or for the greater part of its length ; a deep recess in front 

 of the occipital condyle ; anterior wall of the entrance of the tym- 

 panic cavity constricted. One of the two species is from James 

 Island. 



1. Shell depressed, with the upper anterior profile subhorizontal 

 in the male, and with the striae of the plates not deeply sculptured ; 

 sternum truncated behind. Slcidl with the facial portion very 

 short, and with an immensely developed and raised occipital crest. 

 Testudo elephantopus (Harlan). 



2. Shell much higher, with the upper anterior profile decUvous 

 in the male, and with the striae deeply sculptured ; sternum excised 

 behind. Skull with the facial portion much longer, and with low 

 occipital crest. Testudo nigrita (Dum. & Bibr.). 



B. Shell oblong, smooth. Skull with the palatal region shallow; 

 the outer pterygoid edge expanded in its whole length ; no deep 

 recess in front of the occipital condyle ; anterior -nail of the tym- 

 panic cavity not constricted. 



3. Shell with some traces of former concentric striae, compressed 

 anteriorly into the form of a " Spanish saddle " in the male ; 

 sternum truncated behind. Skull -nith the tympanic cavity much 

 produced backwards. Testudo ephippium (Gthir.), from Charles 

 Island. Extinct. 



4. Shell perfectly smooth, with decKvous anterior profile in the 

 male, and with truncated posterior extremity of the sternum. 



