THE LAND TORTOISES AND TERRAPINS 2413 



They may be divided into four groups, according to their geographical distribution, 

 ach characterized by certain structural peculiarities. The first group comprises the 

 four Aldabra tortoises, characterized by the presence of a nuchal shield on the front 

 of the carapace, and the distinctness of the gulars on the front of the plastron. On 

 the other hand, in the four best-known Mascarene species, constituting the second 

 group, the nuchal shield is wanting, while the two gulars have coalesced into one, 

 the plastron being characterized by its extreme shortness. Lastly, the third, or 

 Galapagos group, with six species, presents a condition intermediate between that 

 existing in the two others, the nuchal shield of the carapace being absent, while the 

 gulars of the plastron remain double. We proceed to notice some of the species of 

 each group. 



The best known of the four species from Aldabra is the elephant 

 tortoise ( T. elephantina] , which differs from the other three in having 

 the horny shields of the carapace concentrically striated, and the plas- 

 tron of the adult notched behind. One of the species ( T. gigantea) with smooth 

 shields on a truncated plastron is peculiar in having the caudal shield divided, as in 

 the Burmese brown tortoise. The elephant tortoise appears to be one of the 

 largest of all the species, attaining a length of about four feet. At the present day 

 it is very scarce in its native island, where the few survivors receive a certain 

 amount of protection from the Government of Mauritius, to which Aldabra belongs. 

 There are, however, a few individuals living in Mauritius and the Seychelles. 



Of the Mascarene species the three species from Mauritius (7! 



indica, trisserrata, and inepta}. all of which are extinct, are character- 

 Tortoises f ' ' 



ized by the thinness of their carapace, of which the margins are thick- 

 ened. The Rodrigues tortoise ( T. vosmaeri) has a still thinner carapace, which in 

 the male does not shelve down in front in the usual manner. Allusion has already 

 been made to the numbers in which these tortoises existed in Leguat's time, but till 

 quite recently it was thought that the species was totally extinct. It appears, 

 however, that in the artillery barracks of Port Louis in the Mauritius, there lives a 

 very ancient tortoise which, in the opinion of Dr. Gunther, is probably of this 

 species. This tortoise is one of two which were imported into the Mauritius by the 

 navigator, Captain Marion du Fresne from the Seychelles in 1766, one of these hav- 

 ing been subsequently presented to the London Zoological Gardens in 1832 by Sir 

 C. Colville. The latter weighed two hundred and eighty-nine pounds, and its shell 

 measured four feet four and one-half inches in length along the curve, and four feet 

 nine inches in width; while in the Port Louis specimen the circumference of the 

 shell is nine feet three inches, and its height two and one-half feet. Marion's tor- 

 toise, as the Port Louis example is called, is thus definitely known to have lived for 

 a hundred and twenty-seven years, and as it was doubtless of large size when 

 brought from the Seychelles, and since all these tortoises take an immense time to 

 reach large dimensions, it is highly probable that it is an actual survivor from the 

 enormous herds that existed in Rodrigues in Leguat's time. From a peculiarity 

 in the structure of the hinder vertebrae of the neck, it appears that the tortoises of 

 this species have the power of raising their necks to a nearly vertical position, 

 which would -give them a wide range of vision. This elevated range of vision 



