200—46 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
Since tlie scute provisionally referred to E. vittata indicates a sliell of about 12 inches 
in length the present specimen belonged to an individual whose shell was probably 
between 18 and 22 inches in length; and the specimen noticed below indicates a still 
larger individual. 
Second specimen . — The posterior two-thirds of a right anterior marginal repre- 
sented from the ventral aspect in fig. 7 of the same plate, although differing slightly 
in outline, agrees so closely in general form, size, and the arrangement of the 
sculpture, that it may be at least provisionally referred to the same species : ■ it was 
likewise obtained by Mr. Theobald from the Siwaliks of the Punjab. The greatest 
width of this specimen is 2 ‘25 inches. 
A third imperfect specimen of the right side in the Indian Museum (No. 135 A), 
with the same history, agrees very closely with the specimen represented in fig. 9. 
Nuchal scute . — The specimen represented in pi. XXVI. fig. 2, comprises rather 
less than the right half of the nuchal scute of an Emyda^ which from its very large 
size and the general agreement in the structure of its sculpture may be pretty safely 
referred to the same species as the marginal scutes noticed above. The specimen 
was obtained by Mr. Theobald from the Siwaliks of the Punjab. 
Before describing this specimen it will be necessary to notice the structure of 
the nuchal scute in the existing species of Emyda ; and in order to exhibit this a 
specimen of this portion of the , carapace of an immature individual of E. granosa, 
in which the entire carapace measures G inches in length, is represented in pi. XXVI. 
fig. 8. It will be seen from this figure tliat in immature specimens the nuchal scute 
consists of two distinct portions ; namely, an anterior subelliptical moiety («), and a 
larger posterior moiety (Z>) of very peculiar shape, which is sufficiently apparent from 
the figure. The anterior border of this posterior moiety is deeply concave in the 
middle for rather more than half its length, the anterior moiety fitting into this 
concavity, to which it is united by cartilage : there is of course no sculpture on the 
anterior surface of the concave portion of the hinder moiety. In fully adult 
individuals the two moieties become united by bone ; the anterior border of the 
scute thus becoming regularly convex, and the sculpture covering the whole of the 
anterior surface. 
The fossil specimen (fig. 2) corresponds to the hinder moiety of the nuchal scute 
of the immature E. granosa ; but differs in that the sculpture extends completely 
over the rounded anterior surface of the concave middle portion of the anterior 
border, clearly showing that the anterior moiety of the recent form (a, fig. 8) was 
never developed in the fossil ; and consequently that the anterior border of the 
nuchal scute was concave at all ages. 
Taking the fossil specimen as representing half the nuchal scute (it really 
comprises somewhat less), the greatest width of the complete nuchal scute would be 
6‘2 inches ; and since the corresponding width of the same scute in the figured 
specimen of E. granosa is 1’9 inches, while the length of the carapace is 6 inches, it 
follows that the length of the fossil carapace Avould be 19'G inches. Allowing for 
