SUPPLEMENTAL REMARKS 



ON THE 



TURTLES FROM THE LONDON CLAY AT HARWICH. 



In the progress of the works now carried on in a part of the Harwich cliffs, with a 

 view to the acquisition of the remains of the animal tissues and bone-earth which 

 form the nodules that are ground up and used as manure, many remains of the 

 Chelonian reptiles which formerly frequented the seas from which those Eocene 

 tertiary strata have been deposited have been discovered. Mr. Colchester, of Little 

 Oakley, Essex, who carries on large works of this kind for the " Fossil Guano," as it 

 is termed, has transmitted to me a number of the nodules in question. The most 

 intelligible and instructive of these I have marked from 1 to 10 consecutively, and 

 shall notice them here in the same order. 



No. 1. Chelone planimentum. This is the half of an oval nodule of petrified clay, 20 

 inches in length, by 17 inches in breadth, exposing an irregular group of disarticulated 

 bones of the carapace and other parts of the skeleton. The species is determined by 

 a fragment of one of the costal plates with the connate rib. The plate measures 2J 

 inches in breadth, the rib 8 lines, and forms the usual partial prominence from the even 

 surface of the under part of the costal plate. Almost the whole of the very broad 

 but short nuchal plate is recognisable : it measures 6 inches in transverse diameter, 

 and only lj inch in antero-posterior diameter. Part of the hyosternal bones, and 

 the impression of the humerus are recognisable. 



No. 2 is the half of a nodule, 20 inches in length and 17 inches in breadth, 

 exposing part of the plastron, and some other bones of the skeleton of the Chel. plani- 

 mentum. It shows well the natural form of the under and outer part of the hyposternal 

 bone, which is much more deeply excavated than in the Chel. crassicostata ; the lower 

 portion of the bone is narrower in proportion to its length, and the xiphisternals are 

 also in proportion longer and narrower than in that species. 



No. 3. Chelone planimentum. The half of an oval nodule, 17 inches in length and 

 13 inches in breadth. The fractured side exposing a cast of the inner surface of the 

 carapace, which measures in length from the nuchal to the tenth neural plate inclusive 

 13tt inches ; and in breadth, across the third pair of costal plates from one end of 

 the projecting rib to that of the opposite side, 1 1 inches. The anterior contour of the 



