Mr. H. G. Seelej on Chelonian Remains. 227 



XXIX. — Note on some Chelonian Remains from the London 

 Clay. By Harry G. Seeley, F.G.S., St. John's College, 

 Cambridge. 



Glossochelys (nov. gen.). 



Chelone harvicensis (Woodward). 

 planimentum (Owen). 



In his description in the Pal^eontographical volume for 1849, 

 Professor Owen states that the carapace is 15 inches long and 

 13 inches wide. The type specimen having perished, there is 

 now no means of verifying these measurements, except from 

 the natural internal cast of the specimen figured. This shows 

 the impression left by the posterior part of the carapace, some- 

 thing of the form of the inner surface of the bones of the an- 

 terior part of the plastron and parts of marginal plates, cora- 

 coid, scapula, and humerus. 



Prof. Owen remarks that in general form this carapace dif- 

 fers from that of the existing Chelones in being less contracted 

 and pointed posteriorly than in Chelone mydas and Chelone 

 caouanna, and more contracted posteriorly than in Chelone 

 imhricata. Attention is also drawn to the great thickness to 

 which the true ribs are developed on the undersides of the 

 costal plates. 



From the posterior termination of what Prof. Owen deter- 

 mines to be the eleventh and last neural plate to the anterior 

 border of the fifth costal plate is rather more than nine inches. 

 From the longitudinal median line of the neural spines of the 

 dorsal vertebrae to the marginal plate beyond the termination 

 of the fourth rib is 7 inches ; the same measurement is found 

 at the fifth rib. The ribs appear to be cylindrical, and termi- 

 nate in obtuse longitudinally grooved rods, of which the naked 

 extremity is not less than an inch long ; they are about | of 

 an inch in diameter, never more. 



The distance from the lateral termination of the fourth rib 

 to the lateral termination of the eighth rib (w^hicli is directed 

 rapidly backward) is 10 inches. The interspace between the 

 terminal ends of the eighth pair of ribs is 5\ inches. 



The interspace between the terminal ends of the eighth and 

 seventh ribs is 3 inches, between the seventh and sixth ribs is 

 2 inches, between the sixth and fifth 1| inch, and between the 

 fifth and fourth about 2 inches. The transverse interspace 

 between the marginal plates and the costal plates seems usu- 

 ally to be about 2 inches, or, according to the carapace figured 

 by Prof. Owen, 1^ incli. 



The termination of the pygal end of the shield is very 



