SIWALIK AND NARBADA CHELONIA." 
23—177 
The 1st costal plate is considerably larger than either of the two succeeding ones/ 
and extends as far back as the middle of the 5th marginal. Tliere are indications 
of the presence of a nuchal plate : and there are distinctly marked areolas, although 
they are not shown in the figures. The first vertebral is wider than either of the 
three following, and is pentagonal, widest anteriorly, with a rounded poste^rior 
border ; its antero-external angles reaching nearly up to the 1st marginal sutures. The 
2nd, 3rd, and dtli vertebrals are hexagonal, narrower behind than in front, and have 
concave borders to their hinder lateral surfaces : in th,e middle of their anterior 
border each of these plates gives off a projection, which is received into a notch in the 
plate in front. The 5th vertebral is not wider than either of the three preceding 
ones ; and the anterior marginal plates are relatively wide antero-posteriorly. The 
absence of any trace of the sutures between the bony scutes indicates the full age of 
the specimen. Its dimensions are as follows, viz . : — 
Length (about) 
6-8 
Length of 3rd vertebral plate 
1-4 
Width 
4-3 
Width ,, ,, ,, 
> > 
1-65 
Height of carapace 
2'5 
Length,, 4th ,, 
1-25 
Length of 1st vertebral plate 
1-55 
Width , , , , , , 
1-6 
Width , , , , , , , , 
1-85 
Length,, 5th ,, 
1-35 
Length,, 2nd ,, ,, 
1-4 
Width „ ,, ,, 
1-6 
W^idth ,, ,, ,, ,, 
1-5 
Distinctness and affinities.- 
—The specimen 
is distinguished 
from 
each of the four 
preceding Siwalik species, as 
well as from the adult of the existing 
C. crassicoUis, by 
the presence of the three indistinct keels and the well-marked areolie : it is j^further 
distinguished from C. punjahiensis (pi. XX. fig. 3.) by the form of the 1st vertebral 
plate; from 0. theohaldi (pi. XX. fig. 2.) by the more elevated carapace, wide 
anterior marginals, much less decidedly mushroom-shaped vertebrals, and shorter 
gulars ; and from 0. hyduspica (pi. XX. fig. 4.) by the great difference in the contour 
and profile of the carapace, and by other characters which are sufficiently evident 
in the figures. It differs still more widely from G. sivalensis (pi. XX. fig. 1.) and 
C. crassicoUis. 
ffdie specimen agrees very closely with the group'"^ comprising G. sinensis from 
Canton and Formosa, C. reevesi from S. China, C. trijuga from India with its allied 
forms from the neighbouring regions, and G. macrocepliala from Siam. Of these 
forms C. reevesi^ is not unlike the present form, but the intergular suture is relatively 
longer, the three middle vertebral plates wider and less constricted posteriorly, the 
costal keels more widely separated from the vertebral keel, and the profile of the 
carapace different. Neither G. sinensis^ nor 0. macroceplial(jd approach very near to 
the fossil ; but G. trijuga comes very close in general form, as is well shown in the 
adult specimen figured by Gray,'' where the inward inflection of the lateral marginals 
1 In figure i the artist has drawn the 1st and 2nd costals too large antero-posteriorly. 
2 Vide Gunther, “ Heptiles of British India,” p. 22. Gunther includes C. crassicoUis, which is, however, distinguished 
by the obliteration of the keels in the adult. 
3 Vide Gray, ” Catalogue of Shield-Eeptiles,” pt. I. pi. V. 
5 Grasy, ‘ Broc. Zool. Soc.’ 1869, pi. XXI. 
4 Vide Gray, loc. cil., pi VII. 
3 ” Catalogue of Shield-Eeptiles,” pt. I. pi. IV. 
