186—32 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
exliibit a large amount of variation, it is extremely difficult to come to a conclusion 
as to what characters in a fossil should be regarded as of specific and what merely 
of individual value. There seems little doubt as to the distinctness of the present 
Siwalik fossil from P. smithi^ P. s>flhetensis^ and P. jlnviventris, as well as from the 
Siwalik s})ecimen provisionally referred to the latter species (fig. 3); while it appears 
equally distinct from P. tectum — or at least from the typical forms of that species. 
With regard to P. tentoria there is perliaps more room for doubt, and the writer 
would have liked a larger series of specimens for comparison. The high pitch of 
the fossil carapace is, however, a character exactly the opposite of that of the living 
form; while the relatively backward position of the 1st costal suture of the former 
and its elongated 2nd vertebral are not characters of the latter. The difference 
between the fossil and recent forms appears decidedly greater than that existing 
between P. tectum and P. tentoria, and in the writer’s 023inion the only possible way 
to identify the fossil with a recent species would be by regarding P. tectum and P. 
tentoria as varieties of one sjcecies, and even then jsuch identification would be 
doubtful. In view, however, of this uncertainty as to the right of the j^resent form 
to specific distinctness it seems advisable not to assigr' it any specific name. 
ddiat this Siwalik Pangshura is an ancestral forix, of the tectiform group of the 
genus is practically certain ; and its somewhat generalized nature is perhaps indicated 
by the backward position of the 1st and 2nd costal sutures, which give indications 
of affinity with the probably still more generalized P. smithi. Both P. tectum and P. 
tentoria may well be descendants of the present form, the very forward position of 
the anterior costal sutures in many examples of the former species (pi. XXII. 
figs. 4. 6.) being an extremely specialized character; the latter conclusion being 
strengthened by the backward flexure of the 2nd costal suture in the Siwalik 
specimen provisionally referred to P. flaviventris (fig. 3). 
Genus III. BATAGUR, Gray.^ 
Including Tetraonyx, Lesson ; Callagur, KacJmga, Dhongoka, Hardella, and 
Cantorelta, Gray. 
It appears impossible to draw up any definition by which this genus (at all 
events in the case of fossils) can be satisfactorily distinguished from Clemmys. The 
species are, however, usually of considerably larger size than those of the latter. 
One species (P. thurgi) is included by Dr. Gunther in Clemmys fEmys). The genus 
is confined at the present day to the Oriental region ; and the species noticed in the 
sequel are believed to be the first fossil forms that have been described. 
Number of species. — The following list comprises the species recognized by 
Messrs. GuntheP and Theobald® : — 
1 “ Catalogue of Shield-Eeptiles in Brit. Mus.” p. 35. (1855). 
2 “Reptiles of British India,” pp. .37-43. 
“ Catalogue of lloptiles of British India,” pp. lU-25. 
