[361] The term Inoceramus is restricted by the French geologists to the beaked and laminated species of the Galt; and the chalk Inocerami are arranged under the name Catillus.
[362] Perna and all the Aviculidæ have the same structure, Inoceramus scarcely differs from Perna.
[363] Dr. Carpenter on the Microscopical Structure of Shells. To detect this structure, the shell should be immersed in diluted hydrochloric acid, and when partially dissolved, the cells will be apparent.
[364] It was many years before I succeeded in obtaining a specimen with the hinge perfect; and M. Brongniart, unable to obtain one from the chalk of France, gave the figure of this genus from my Foss. South D. pl. xxvii. in the Géog. Min. Env. de Paris.
In the Galt, or Folkstone-marl, two small species of this genus are to be found in every locality I have visited. They were first figured and described by Mr. Parkinson, under the name of Inoceramus sulcatus, and I. concentricus (Wond. p. 330, fig. 1 and 3). In most examples the shell is in the state of a white, friable earth, and readily decomposes, leaving patches of iridescent nacre on the casts; but I have seen examples which prove that the originals were of a fibrous structure, like the Inocerami of the Chalk.
Lign. 130. Flint, with fragments of Inoceramus.
Chalk. Lewes.
a. Marks the section of a fragment of shell, with numerous cavities, occasioned by the depredations of Cliona Conybearei.
b. Portion of shell partially decomposed, and exposing siliceous, globular bodies, connected by filaments, which are flint casts of the hollows left by the Cliona.