320 DE. HANS GADOW ON EBMAINS OF SOME GIGANTIC 



peculiarities which are characteristic of the Mauritian T. indica, T. triserrata, and 

 T. inejpta, and also resembling in several points some of the Galapagos species ^ 



Complexes of terminal Caudal Vertehrce (Plate XLIII. figs. 1, 2, 3). — Until proof 

 to the contrary is forthcoming, I assign two completely preserved specimens of 

 anchylosed terminal vertebrae to the species which possesses the cleft or forked 

 plastron, namely T. sumeirei. The largest of these curious specimens measures 

 12 cm. in length, with an anterior concave, almost saddle-shaped, articulating facet of 

 5'3 cm. in width. The anterior half of this vertebral complex consists clearly of three 

 or four anchylosed vertebrae, while the posterior half, strongly curved downwards and 

 tapering to a blunt point, shows by its surface-mouldings that it was covered with a 

 horny sheath which completely surrounded the terminal half like a spur. The length 

 of this spur was at least 6 cm., to which, of course, the probably considerable thickness 

 of the horn itself has to be added. 



Dr. Giinther says in his description of T. elephantina (Monograph, p. 30) that " the 

 last seven vertebrae are quite rudimentary and coalesced into a single bone." The 

 total number of caudal vertebrae of T. elephantina is 25, i. e. 18 free vertebrae besides 

 the coalesced complex ; the shell of the large stuffed male specimen in the Natural 

 History Museum is not less than 49 inches long, but the caudal complex is far less 

 completely anchylosed, and its anterior articulating facet is one third smaller than is 

 the case with the two specimens in Mr. Sauzier's collection. They either belonged to 

 a Tortoise of gigantic dimensions (as indicated by the large plastron E), or the caudal 

 spurred complex is relatively larger than in any of the Aldabran races. According to 

 Perrault's description, T. indica likewise possessed a distinct horny spur. Dr. Giinther 

 continues as follows : — " In individuals of the male sex the tail plays a very important 

 part as an external prehensile or, rather, steadying organ, which also differs externally 

 from that of the female in its greater length and by being provided with a large 

 terminal claw. Nearly always the animal carries it bent sidewards under the carapace, 

 generally towards the left side, and therefore I anticipated to find a want of symmetry 

 in some portion of the root of the tail ; however, nothing of the kind can be observed." 



I have much pleasure in corroborating the sagacious anticipation of Dr. Giinther 

 concerning an asymmetrical development, not, however, of the root of the tail, but of 

 the terminal half of the anchylosed complex, which shows a distinct deviation towards 

 the left side (see figure of dorsal view, Plate XLIII.). 



Among gigantic Land-Tortoises such an anchylosis has hitherto been observed only 

 in specimens from Aldabra, Mauritius, and, to a lesser extent, from the Galapagos. 

 In one specimen of T. elephantopus the vertebrae are, according to Giinther, " irregular, 

 and asymmetrically confluent towards the end of the tail." 



' Should the post-mortem of the solitary surviving type of T. sumeirei reveal that it differs in its plastron 

 from those referred to as D, E, F, G, I herewith reserve to myself the claim of distinguishing these forked 

 plastra as belonging to a Testudo guentheri. 



