314 DR. HANS GADOW ON EEMAINS OF SOME GIGANTIC 



view was to be accepted as possible, considering that the island of Aldabra has yielded, 

 according to Dr. Giinther, five living species, which Mr. Boulenger has reduced to four. 

 But now, through this last collection, there have come to light so many different 

 forms of Tortoises that, proceeding upon the old lines, at least the following forms 

 have to be distinguished : — 



T. INDICA, provided carapace No. V. belongs to this form. 



T. TRISEKRATA. 

 T. INEPTA. 

 T. SAUZIERI. 



T. SUMEIEEI, i. e. the name given by Mr. Sauzier to the specimen which is still living 

 in the court of the Artillery Barracks at Port Louis. 



Lastly, T. leptocnbmis, if need be. 



This makes five or six different forms, and to suppose that these represent as many 

 species reduces the idea of a species to absurdity, unless the very presence of these 

 Tortoises on this little island (and the same applies to Aldabra) be explained by the 

 thrilling assumption that during the supposed process of subsidence of the surrounding 

 country — now the Indian Ocean — the Tortoises fled to the highest districts, now the 

 islands of Madagascar, Aldabra, Mascarenes, &c. This assumption implies the 

 supposition, equally gratuitous, that South-western " Lemuria " was inhabited by at 

 least 11 to 14 different species of gigantic Tortoises, namely 5 or 6 now in Mauritius, 

 4 or 5 now in Aldabra, 1 in Rodriguez, and 1 or 2 in Madagascar, not counting 

 the species which possibly never reached these islands. 



How these islands ever received their Tortoises is a mystery, but this is quite another 

 question. 



The five or six forms of Galapagos Tortoises were, or are, to a certain extent 

 peculiar to difi'erent islands, and this isolation is in favour of their specific value, but 

 five of the Mauritian forms were all found in the same swamp i. With plenty of food, 

 a congenial climate, and without formidable enemies, they grew to a gigantic size, could 

 interbreed to their hearts' content, for all we know to the contrary, and variation 

 within harmless bounds received no check from natural selection. The very thinness 

 of the shells of some of these gigantic Tortoises, especially T. vosniaeri of Rodriguez 

 and several Galapagos forms, seems to indicate that strength of the dermal armour was 

 no longer required in these Elysia of Tortoises. 



' I do not suggest that different genera, and even different species of one genus, do not inhabit the same 

 locality. In the marismas of Andalucia I have found, in the Laguna de los Patos, Emys eurojicea and 

 Chmmys sir/ris s. leprosa in equal numbers, a somewhat unexpected fact, because Emys is the almost exclusive 

 Tortoise in North Portugal, whUe Olemmys is extremely abundant in the Alemtejo, where Emys is very rare. 



