60 
INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
oneof which is covered with the ‘ spat ’ of oysters, while sharks’ teeth are embedded 
in the matrix of the other. The affinities of the Chelonians show, however, that 
their habitat could only have been estuarine, since they belong to essentially 
fresh-water families. Both specimens when placed in the hands of Mr. Barlow, of 
the British Museum, to be ‘ developed * were in a much broken condition, and from 
being traversed by numerous veins of calcspar, along which they readily split, it 
required all his skill to render them fit for description. 
It should he mentioned that the only fossil Indian Chelonian from below the 
level of the Siwaliks (where all the forms are more or less closely allied to those 
now inhabiting India, and adjacent regions) which has been hitherto described is 
Platemys leithi 1 (Carter) from the intertrappeans (lower eocene) of Bombay, which 
is a small species with a shell of about five inches in length. Platemys, it need 
hardly he observed, is a member of the sub-order Pleurodira, now characteristic of the 
Southern Hemisphere, and is itself confined at the present day to South America. A 
chelonian has been recorded by Sir R. Owen 1 2 from the lower eocene of England under 
the name of Platemys bowerbanki, hut Professor Rutimeyer 3 has shown that this 
generic determination is incorrect ; and that the presence of an incomplete meso- 
plastral element in the plastron indicates affinity with the South American genera 
Peltocephalus or Podocnemis, although the imperfect preservation of the type speci- 
men renders its precise determination a matter of considerable difficulty. The same 
authority also shows that the specimen figured by Owen 4 5 under the name of Emys 
Icevis, Bell, is nothing more than the young of the above-mentioned species ; and it 
may he added that the length of the band uniting the carapace with the plastron in 
this specimen is indicative of affinity with Podocnemis rather, than Peltocephalus , 
and it has been provisionally referred to the former genus by the present writer and 
Mr. G. A. Boulenger ; 6 that genus being represented by another species in the 
same formation. A plastron, said to be from the London clay, was also referred by 
Sir R. Owen 8 to Platemys, under the name of P. bullocki ; hut this specimen is 
really from the Purbeck, and belongs to the genus Pleurosternum . 7 
It will suffice to add in the way of introduction that in the memoir on the 
Siwalik Chelonia published in Yol. Ill of the present work, the term * scute ’ is 
applied to the bony framework of the Chelonian shell, and ‘ plate * to its horny 
epidermal covering ; but, as this has been thought liable to lead to confusion the 
terms * hone ’ and ‘ shield ’ are employed here in these senses. 
1 Originally described as Testudo, but referred by Gray to Hydraspis, which is now generally included in 
Platemys ; see ‘ Rec. Geol. Surv. Ind.’ Vol. XX, p. 66 (1887). 
2 Monograph of Reptilia of London Clay — Chelonia I, PI. XXIII (1849). 
* * Ver. Nat. Ges. Basel,’ Vol. VI, Art. 1, pp. 121, 128 (1878). 
4 Op. cit., pi. XXII. 
5 Geological Magazine, June 1887. 
6 Ibid., pi. XXI. 
7 See Lydekker and Boulenger, op. cit. Cope, ‘ Tertiary Vertebrata of the West ’ (Rep. U. S. Geol. Surv. Ters. 
Vol. Ill) book 1, p. Ill (1884), makes Pleurosternum the type of a distinct family of Cryptodira, and erroneously 
states that there is no intergular shield. 
