180—26 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
Extreme length of shell (margins 
partly broken 
in fossil) 
Small 
Fossil. 
Clemmys 
hamiltoni. 
8-6 
Large 
Fossil. 
11'7 
Extreme width of ditto 
3-45 
5-9 
8-1 
Height of ditto 
2-7 
4-1 
5-4 
Length of plastron 
7-8 
11-5 
Width of ditto between keels 
2-3 
3-85 
5 2 
Interval between axillar}' incisions 
2-4 
3-9 
5-4 
Ditto ,, inguinal ,, 
1 95 
3-4 
4-8o 
Length of 1st vertebral plate 
1-16 
1-65 
2-5 
Width ,, ,, ,, ,, 
0-87 
1-5 
1-75 
Length ,, 2nd ,, ,, 
1-07 
1-65 
2 24 
Width ,, ,, ,, ,, 
1-1 
1-55 
2-1 
Length ,, 3rd „ ,, 
11 
1-55 
2-2 
Width ,, ,, ,, ,, 
1-12 
1-52 
2-12 
Length ,, 4th ,, „ 
15 
2-2 
W^idth ,, ,, ,, ,, 
1-65 
2-44 
Length ,, 5th ,, ,, 
1-6 
2-05 
W^idth , , , , , , , , 
2-22 
3-0 
It will be seen from these measurements that tlie recent and fossil forms agree 
very closely in general proportions : the 2nd and 3rd vertebrals are indeed of 
slightly greater relative width in the smaller fossil, but this difference is not nearly 
so great as in young and old specimens of C. hamiltoni. The adult of that species is 
distinguished from the fossil sliells by the narrower nuchal plate, by the marked 
concavity of the profile of the anterior portion of the shell, by the keel on the 1st 
vertebral being lower and confined to the hinder part of the plate, by the 1st 
vertebral being widest anteriorly, and by the decidedly lesser degree of development 
of all the vertebral and costal keels. In very young specimens of the living species 
(l^late XXI. fig. 2), which are those more commonly observed in English collections, 
the costal keels form a regular curve, instead of being parallel as far back as the 4th 
vertebral plate, and are placed more remotely from the vertebral keel : the vertebral 
plates are, moreover, proportionately so much wider that their width exceeds their 
length : the anterior profile of the carapace is less markedly concave. An apparently 
allied form from Siam has been described by Gray^ as Clemmys macrocephala ; the 
shell is, however, depressed, and the keels end abruptly at the 3rd vertebral plate. 
Clemmys nigricans from S. China and G. reevesi from Canton and Formosa are unlike 
the Siwalik form. 
That the latter is closely related to, and probably the ancestral form of, Clemmys 
hamiltoni there seems no reasonable doubt. As, however, it appears to differ from 
the living species as much as several of the allied living species do from one another, 
it seems allowable to assign it a distinct name ; and it is accordingly proposed that 
it should be called Clemmys palwindica. 
According to Mr. Theobald‘S the living C. hamiltoni is confined to Lower Bengal. 
D. Generic position uncertain. 
Clemmys (?) sp. 7. 
History . — In 1859 Falconer^ referred to a specimen now in the Indian Museum 
1 Vide ‘ Supplement to Catalogue of Shield-Reptiles,” pt. I. p. 43 [Dantonia) 
2 “ Catalogue of Reptiles of British India,” p. 11. 
3 Catalogue of Fossil Vertehrata in Museum of Asiatic Society of Bengal,” p. 209. No. P. 114. 
