578 
Prof. Bell, which exhibits well the charaeter 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 
great; since the Hmys or Cistudo HKuropea still abounds on the Con- 
tinent, and liyes long in our own island in suitable localities: but 
the case assumes a yery different aspect when we come to the con- 
viction, that the majority of the Sheppey Chelonites belong to the 
true marine genus Chelone; and that the number of species of the 
Eocene extinct turtles already obtained from so limited a space as 
the isle of Sheppey exceeds that of the species of existing Chelone. 
Notwithstanding the assiduous search of naturalists, and the attrac- 
tions to the commercial yoyager which the shell and the flesh of the 
turtles offer, all the tropical seas of the world have hitherto yielded 
no more than five well-defined species of Chelone, and of these only 
two, as the C. Mydas and C. caretta, ave known ta frequent the same 
locality, 
It is obyious, therefore, that the ancient ocean of the Hacene epoch 
was less sparingly inhabited by turtles; and that these presented a 
greater variety of specific modifications than are known in the seas 
of the warmer latitudes of the present day. 
The indieations which the Sheppey turtles afford of the warmer 
climate of the latitude in which they lived, as compared with that 
which prevails there in the present day, accord with those which all 
reference to this interesting point. 
That abundance of food must have been produced under such in- 
fluences cannot, Mr. Owen states, be doubted ; and he infers, that to 
some of the extinet species—which, like the C. coniceps and C. platy- 
gnathus, exhibit either a form of head well adapted for penetrating 
the soil, or with modifications that indicate an affinity to the Trio- 
nyxes—was assigned the task of checking the undue increase of the 
extinet crocodiles of the same epoch and locality, by devouring their 
eggs or their young, becoming probably, in return, themselves an oc- 
casional prey to the older individuals of the same carnivorous saurian, 
