CRETACEOUS FORMATIONS. 11 



any very distinct character of suture, but appear to have been joined by a wavy 

 line. The length of the rib which projects beyond the conjoined costal plate is con- 

 siderable, being proportionally greater than in the much smaller Chelone Benstedi ; and 

 the free portion of the rib is narrower, with a smoother upper surface, evidently indi- 

 cating a distinction of species. The portion of carapace in question may belong to a 

 young Chelone Camperi. 



Of the marginal plates of that species only the anterior ones appear, as yet, to 

 have been discovered at Maastricht ; but the liability of such slightly attached parts 

 to be scattered and lost, renders their discovery in natural connection, as in the speci- 

 mens in T. V, more remarkable, perhaps, than their absence, and affords, at least, no 

 sufficient grounds for the speculation of Faujas St. Fond, that they were cartilaginous 

 in the large Turtle from Maastricht. The outer surface of the bones of the carapace 

 of the Chelonian Reptiles which actually retain the marginal plates in a gristly state, 

 is characterised by a sculptured character, well shown in several plates of a former 

 Monograph, ex. T. XVI, but of which no trace exists in the Chelone Camperi, from 

 Maastricht, any more than in the neural or marginal plates in Tab. V, or the costal 

 plates in Tab. VI of the Chelonites from the upper chalk of Kent. 



Chelones indeterminate. 



Various portions of the fossilised skeletons of Chelonian Reptiles have been kindly 

 submitted to me by Mrs. Smith, of Tonbridge Wells ; by J. S. Bowerbank, Esq. ; 

 and by Thomas Charles, Esq., of Maidstone, from which specimens I have selected 

 the subjects figured in T. IV, T. VI, and T. VII A. 



The specimen, fig. 8, T. VII A, from the Collection of J. S. Bowerbank, Esq., is of 

 a similar nature to those above described and figured in T. V ; but it is rather 

 smaller, and is more decidedly shown to belong to the marginal series of scutes by the 

 unsymmetrical development of the two sides which slope away from the median 

 ridge ; and this, also, is oblique : the sides form a less open angle : their substance, 

 which is hardly a line in thickness at the meridian ridge, gradually thins off to the 

 border, which is produced on one side into a number of dentated processes, that to 

 all appearances are natural." 



There are two similar but rather smaller marginal scutes in the same Collection. 



Mr. John Quekett, the Assistant Conservator of the Museum of the Royal College 

 of Surgeons, has kindly prepared sections for the microscope from the preceding 

 specimens, and the form, size, and arrangement of the bone-cells agrees with those in 

 similar preparations from the scutes of the recent Turtle. 



The portion of mandible, T. VII A, figs. 4 and 5, resembles that of the Chelone 

 planimentum, T. IX, of a former Monograph, and of some of the Eocene Turtles from 

 Bracklesham, figured in Mr. Dixon's work ' On the Tertiary and Cretaceous Deposits 

 of Sussex,' Tab. XIII, in the great extent of the bony symphysis; but this differs in 



