889.] R. Lydokker — On the Tortoises described as Cliaibassia. 



333 



Having now sufficiently (iiscussed tlie affinities of the recent form it 

 remains to say a few words in regard to the fossil shell, of which a figure 

 of the doi'sal aspect is given in Fig. 2. The contour of the carapace is so 

 essentially that of the recent form that there can be but little hesitation 

 in referring the fossil specimen to the recent species. This conclusion is 

 confirmed by the circumstance (which first led me to think that the 

 fossil was allied to the so-called Cliaibassia) that the hypoplastrals had 

 a ligamentous union with the carapace, as is shown by the smooth 

 surface on the inner side of the inguinal marginals. The fossil shell 

 is, however, decidedly larger than that of the existing race, its length 

 when entire having been about 17 centimetres. The first and second 

 vei-tebi-al shields are also relatively wider than in either of the existing 

 examples ; while all the vertebrals tend to assume a more decided 

 balloon-shape in the fossil, which it may therefore be convenient to 

 regard as a distinct race under the name of Nieoria tricarinata, var. siva- 

 lensis. The fossil specimen agrees with the recent Sirguja example in 

 the total obliteration of all the satures between the component bones 

 of the carapace. 



Fig. 2. Carapace of Nieoria, trieannata, var. sivaletisis, from the Pliocene of tlio 

 Siwiilik Uills, J. int. size. The nem-al bones are restored in outliiie from N. trijiuja- 



