of the Remains of Marine Turtles from the London Clay. 377 



species of which the skull is here described with the Chelonite figured 

 in the frontispiece to Woodward's ' Synoptical Table of British 

 Organic Remains,' and alluded to without additional description or 

 characters as the ' Chelonia Harvicensis ' in the additions to Mr. 

 Gray's 'Synopsis Reptilium,' p. 78, 1831; and since it is highly 

 probable that the extensive deposit of Eocene clay along the coast of 

 Essex, like that at the mouth of the Thames, may contain the relics 

 of more than one species of our ancient British turtles, the author 

 prefers indicating the species here described by a name having refer- 

 ence to its peculiarly distinguishing character, to arbitrarily associa- 

 ting the skull with any carapace to which the vague name of Harvi- 

 censis has been applied. 



Besides the specimen of Chelonite from Harwich, in the museum 

 of Norwich, figured by Woodward, there is a mutilated carapace of 

 a young Chelone from the same locality in the British Museum. 

 This specimen exhibits the inner side of the carapace, with the heads 

 and part of the expanded bodies of four pairs of ribs. It is not suf- 

 ficiently entire to yield good specific characters, but it demonstrates 

 unequivocally its title to rank with the marine turtles. It is figured 

 in Mr. Kcenig's ' Icones Sectiles,' pi. xvi. fig. 192, under the name 

 of Testudo plana. 



The carapace of a larger specimen of Chelone, from the coast of 

 Harwich, was purchased, by the British Museum, of Mr. Charles- 

 worth, by whom a lithograph of the inner surface of this Chelonite, of 

 the natural size, has been privately distributed, without description. 



The carapace in the museum of Prof. Sedgwick, forming part of 

 the same individual (Chelone planimentum) as the skull above described, 

 exhibits many points of anatomical structure more clearly than the 

 last-mentioned Chelonite in the British Museum ; it also displays the 

 characteristic coracoid bone of the right side in its natural relative 

 position. The resemblance of this carapace in general form to that 

 of the Chelone caretta is pretty close ; it differs from that and other 

 known existing turtles, and likewise from most of the fossil species, 

 in the thickness and prominence of the true costal portions of the 

 expanded vertebral ribs, which stand out from the under surface of 

 the plate through their entire length, and present a somewhat angular 

 obtuse ridge towards the cavity of the abdomen. 



In the large proportional size of the head, the Chelone planimentum 

 corresponds with the existing turtles ; and that the extinct species 

 here described attained larger dimensions than those given above, is 

 proved by a fossil skull from the Harwich clay, in the collection of 

 Prof. Bell, which exhibits well the character of the broad and flattened 

 symphysis. 



A carapace of a smaller individual of Chelone planimentum from the 

 Harwich coast, with the character of the inwardly projecting ribs 

 strongly marked, is likewise preserved in the choice collection of the 

 same excellent naturalist. One of the hyosternal bones enclosed in 

 the same nodule of clay testifies to the partial ossification of the 

 plastron in this species. 



In the summary of the foregoing details the author observes, that 

 Phil. Mag. S. 3. Vol. 21 . No. 1 39. Nov. 1842. 2 C 



