[684] Rep. Brit. Assoc. 1841, p. 177, and Monograph on Fossil Reptiles, Pal. Soc. 1849, in which the anatomical details are given with the characteristic accuracy and minuteness of the author.
The Tertiary formations of India, however, have furnished decided examples of fossil terrestrial tortoises; and among the innumerable relics of the beings of an earlier world, which the indefatigable labours of Dr. Falconer and Captain Cautley have brought to light, and which those accomplished naturalists have so skilfully developed, are the remains of land tortoises of prodigious magnitude (Colossochelys atlas); one specimen indicating a length of twelve or fourteen feet, with a breadth and height of corresponding proportions! These remains are associated with the bones gigantic extinct mammalia, allied to the Palæotheria and other pachyderms of the eocene deposits of the Paris basin; and with those of Emydian and Crocodilian reptiles.[685]
[685] Petrif. pp. 11 and 468.
Fossil Marine Turtles.—In illustration of this subject, I select a specimen discovered in the lower Chalk, at Burham, Kent, which is remarkable for its beautiful state of preservation, and its peculiar osteological characters.
Lign. 238. Chelone Benstedi: nat. size.
Chalk. Kent.
The dorsal shield or carapace of this specimen admits of being removed; and four sternal plates, a coracoid-bone, and several vertebræ are then exposed.
Chelone Benstedi. [Lign. 238].—To Mr. Bensted, of Maidstone, whose discoveries have rendered his quarry of Kentish Bag classic ground to the British palæontologist, I am indebted for this splendid fossil turtle. The quarry whence it was obtained is situated at Burham, a short distance from the banks of the Medway, between Chatham and Maidstone, and presents a good section of the lower Chalk. This locality is rich in fossil remains, rivalling in this respect the quarries near Lewes, Worthing, and Arundel, in Sussex. Two other fossil Turtles have been obtained from this quarry, and now enrich the cabinets of Sir P. Egerton and Mr. Bowerbank. Other relics of Chelonians found in this place are four marginal plates of the carapace, and fragments of ribs,[686] some marginal plates of a much larger individual, mandibles, and other fragments, which are noticed in Prof. Owen’s Monograph, 1851. The specimen, of which [Lign. 238] is a reduced figure, consists of the dorsal buckler or carapace almost entire; it is of a depressed elliptical form, with a longitudinal median ridge; it is six inches in length, and three and a half inches in breadth across the middle. It is composed of eight ribs, or costal plates, on each side the dorsal ridge, which is formed of ten neural plates; and there is a border of marginal plates. These plates are united to each other by finely indented sutures, and bear the imprints of the horny scutes, or tortoise-shell, with which they were originally invested. The expanded ribs are united throughout the proximal half of their length, and gradually taper to their marginal extremities, which are supported by the plates of the osseous border.[687] This description applies to the specimen as seen in [Lign. 238]; but Mr. Bensted so skilfully cleared away the chalk as to admit of the removal of a great part of the dorsal shield, by which means some of the vertebræ, four sternal (hyosternal and hyposternal) plates, and one of the coracoid bones are displayed. This brief description will suffice to convey a general idea of the characters of this fossil, which differs from any known recent turtle, and possesses some anomalous features, that appear to indicate some slight Emydian affinities.
[686] See Geol. Proceed, vol. iii. p. 299.
[687] See also Phil. Trans. 1841, p. 153, pl. xi. and xii.; and Palæontograph. Monograph, 1851, p. 4, plates i. ii. and iii.