156 BRITISH FOSSIL REPTILES. 



late father-in-law, William Clift, Esq., F.R.S., there is one of a carapace of a large 

 fossil Turtle, corresponding in size with that mentioned by Camper, and in his style 

 of drawing. It is entitled " Tortue petrifiee trouvee dans la Montagne de St. Pierre 

 pres de Maestricht ;" and exhibits the "nuchal" and anterior "marginal" plates; 

 ten " neural " plates, of a rhomboidal figure, carinated, and of nearly equal size, the 

 fifth being six inches in diameter : the eight costal plates of the left side, and the first 

 two and last three of those on the right side. The length of the first costal plate is 

 seven inches, that of the last is little more than three inches ; remains of the long and 

 slender ribs are shown extending from the apices of the costal plates, which, in 

 proportion to the length of the entire carapace, and to their own antero-posterior 

 diameter, which is five inches, are extremely short, for in a carapace of a Turtle four 

 feet in length, the costal plates must be supposed to have attained their full extent of 

 ossification. The transverse diameter of the neural plates in this large fossil Turtle 

 from Maestricht is three fourths that of the costal plates at the fore-part of the 

 carapace, and is greater than that of the costal plates at the hind part, — a proportion 

 which I have not noticed in any other Turtle, recent or fossil. The same characters 

 appear in the figures given by M. Faujas St. Fond, of the same large species of Turtle.* 

 CuviER, whose superior anatomical knowledge enabled him to coiTect some erroneous 

 remarks which M. Faujas St. Fond had published respecting the Chelonian remains in 

 his ' History of the Fossils of St. Peter's Mount,' arrives at the conclusion, that they 

 belonged to the Turtles, or marine genus Chelone, and to a species distinct from any 

 existing Turtle ;t but he does not notice the character of the great breadth of the 

 neural plates, as compared with that of the costal ones ; he only remarks that the great 

 Maestricht Turtle appears to have much resembled the Chelone carcfta. 



The formation, near Maestricht, in which these Chelonian fossils occur, is the most 

 recent member of the deposits of the Secondary epoch, — the highest and last formed 

 of the cretaceous group : it consists of a soft yellowish stone, not very unlike chalk, 

 and includes " siliceous masses, which are much more rare than those of the chalk, of 

 greater bulk, and not composed of black flint, but of chert and calcedony, J 



Fossil remains of the Chelonian Order were deemed to be of rarer occurrence in 

 the Chalk formations of England, which are apparently of older date than those at 

 Maestricht. The first intimation of such was given by Dr. Buckland, in his ' Bridge- 

 water Treatise' (1836), vol. ii, p. 67, pi. 44', fig. 2id, which is described as a "beak of a 

 small testudo from chalk, in the collection of Mr. Mantell, showing a fibro-cancellated 

 bony structure, very different from the compact shelly condition of the Rhyncolite, for 

 which it may, from its size and shape, be mistaken." Dr. Mantell states, in his 

 ' Wonders of Geology' (1839), vol. i, p. 330, that this specimen is " from the Lewes 



* Histoire Naturelle de la Montagne de Saint-Pierre de Maestricht, 4to, 800, pi. xii-.\iv. 

 t Ossemens Fossiles, 4to ed. 1824, torn, v, pt. 2, p, 242. 

 I Fitton; Proceedings of Geol. Soc, 1830. 



