p CHELONIA. ^ 7 



The scapular and pelvic arches, and the bones of the extremities of the Chelonia, 

 are described and figured in the ' Ossemens Fossiles' of Cuvier ;* where, also, the 

 figures of the modifications of the carapace and plastron, in the fresh-water and land 

 tortoises, will suffice for the purpose of ulterior comparisons with the fossils described 

 in the present work, if they be understood according to the homologies above 

 discussed, and which are illustrated by the figures 1 and 2 of the carapace, and fig. 3 

 of the plastron of the Chelone caouanna. 



With regard to the more immediate subjects of the present Monograph, it must 

 be admitted that the important generalizations of Cuvier and Dr. Bucklandf have 

 been confirmed, but not materially extended, by subsequent observations on the remains 

 of reptiles of the Chelonian order. Cuvier, after admitting that his results in regard 

 to the tortoises were not so precise as those relating to the crocodiles, sums up his 

 chapter on the fossil Chelonia in the following words : "Toutefois nous avons pu nous 

 assurer que les tortues sont aussi anciennes dans le monde que les crocodiles ; qu'elles 

 les accompagnent generalement, et que le plus grand nombre de leurs debris appartenant 

 a des sous-genres dont les especes sont propres aux eaux douces ou a la terre ferme, 

 elles confirmentles conjectures que les os de crocodiles avoient fait naitre sur I'existence 

 d'iles ou de continens nourissant des reptiles, avant qu'il y ait eu des quadrupedes 

 vivipares, ou du moins avant qu'ils aient ete assez nombreux pour laisser une quantite 

 de debris comparable a ceux des reptiles. ";|: 



Dr. Buckland also states, in general but precise terms, that '' the Chelonian reptiles 

 came into existence nearly at the same time with the order of Scmricms, and have 

 continued coextensively with them through the secondary and tertiary formations unto 

 the present time. Their fossil remains present also the same threefold divisions 

 that exist among modern Chelonia into groups, respectively adapted to live on land, in 

 fresh water, or the sea."§ 



The remains of sea turtles {Chelone) have been recognised in the Muschelkalk, the 

 Wealden, the lower cretaceous formation at Claris, and the upper chalk-beds at 

 Maestricht. Figures of Chelonites, as that in the Frontispiece to Woodward's 

 ' Synoptical Table of British Organic Remains,' and in Konig's ' Icones Sectiles' 

 ,(pl. xviii, fig. 232, a and b), have been published ; but no true marine Chelonian, from 

 Eocene strata, had been scientifically determined prior to the communication of my 

 Paper on that subject to the Geological Society of London. || All the Chelonites from 

 Sheppey, described and figured in the last edition of Cuvier's ' Ossemens Fossiles,' for 



* Tom. V, pt. 2, pi. xii and xiii. 



t Bridgewater Treatise (1836), p. 256. 



X Ossemens Fossiles, 4to, torn, v, pt. ii, p. 249. 



^ Bridgewater Treatise, p. 256. 



II Proceedings of the Geological Society of London, vol.iii, pt. ii, p. 570, December 1, 1841. 



