UR. MANTELL ON THE FOSSIL REMAINS OF TURTLES. 
155 
Trionyx. The remains of land Tortoises are found at Aix, and in the London clay 
of the Isle of Shepey. 
Lastly, the deposits which have been formed during the modern epoch, contain 
the osseous relics of marine, lacustrine, and terrestrial Testudinata ; as, for example, 
the calcareous strata beneath beds of lava in the Isle of France* ; while in the accu- 
mulations of detritus which are still in progress, similar remains are being entombed, 
as in the modern conglomerates on the shores of the Bermudas, and of the Isle of 
Ascension, in which the bones and even eggs of Turtles are daily becoming imbedded 
and preserved'}'. 
As, from the extreme rarity of Chelonian remains in the cretaceous deposits of 
Great Britain, any well-preserved relics of this kind possess considerable geological 
interest, I beg to lay before this learned Society a description, with figures, of a re- 
markable fossil Turtle from the chalk of Kent. I am indebted for this specimen to 
Mr. Bensted of Maidstone, a gentleman whose zeal for the advancement of palaeon- 
tology I have already had occasion gratefully to acknowledge. This fossil, which 
has been delineated of the size of nature by M. Dinkel, in the annexed drawings 
(Plate XI. and XII.), consists of the carapace or dorsal shell of a small Turtle, with 
some of the sternal plates, vertebrae, and one of the coracoid bones. It was obtained 
by Mr. Bensted from a quarry of the lower chalk at Burham, which is situated at 
a short distance from the banks of the Medway, between Chatham and Maidstone. 
This locality had already obtained some celebrity from having furnished several good 
specimens of fossil fishes of the genus Beryx, of the same species with those disco- 
vered by me in the chalk near Lewes, in Sussex, and which have been figured by M. 
Agassiz;};. The mandibles of a Chimera, teeth of the shark family, remains of Crus- 
tacea, Ammonites, Nautili, Inocerami, and the usual shells of the lower chalk, with 
fuci ( Fucoides Targionii ) and fragments of wood, have also been collected in the same 
quarry. The only portion of a Chelonian reptile that had been obtained from the 
chalk-pit at Burham, before the discovery of the specimen which forms the subject 
of the present communication, was a fragment described by Professor Owen in a 
paper lately read before the Geological Society of London. This fossil comprises 
four marginal plates of the carapace, and some small fragments of the ribs, of an in- 
dividual not exceeding in size the present example. The marginal plates are united 
by the usual finely indented sutures, and each is impressed along the middle of its 
upper surface with a line corresponding to the margin of the horny plate by which it 
w r as originally defended. The external edge of each plate is slightly emarginated in 
the middle. “ These plates,” Mr. Owen observes, “ are narrower in proportion to 
their length than those of any of the existing marine Chelonia ; and they deviate still 
more in the character of their internal articular margin, from the corresponding parts 
of terrestrial tortoises. But they sufficiently agree with the marginal plates of the 
* Ossemens Fossiles, tom. v. p. 248. t Wonders of Geology, p. 78. 
+ Recherches sur les Poissons Fossiles. 
MDCCCXL1. 
Y 
