ABSTRACT
The shell is generally depressed, and broadly oval or almost circular; in Chelonobia testudinaria and caretta, it has a massive appearance: the surface is generally smooth, or, when disintegrated, finely striated: the colour is white. As soon as the surface was once ruptured, the shell of the Chelonobia, growing outwards and downwards, would easily, like a wedge, turn up the laminae of the tortoise-shell; and their ragged ends would surround the Chelonobia, as is seen actually to be the case. The radii, when the compartments are disarticulated, present a remarkable structure, from appearing to consist of a distinct inner and outer portion. The alae are of moderate thickness, and have their sutural edges crenated by fine transverse septa. In Chelonobia caretta, the line of separation between the inner and outer laminae can in no part be distinguished, owing to the interspaces between the septa having solidly filled up, close down to the basis.
