A Manual of Elementary Geology / or, The Ancient Changes of the Earth and its Inhabitants as Illustrated by Geological Monuments

by Sir Charles Lyell

Crania Parisiensis, inferior or attached valve. Upper white chalk.

Fig. 206.

Plagiostoma Hoperi, Sow. Syn. Lima Hoperi. White chalk and upper greensand.

Fig. 207.

Plagiostoma spinosum, Sow. Syn. Spondylus spinosus. Upper white chalk.

Among the rest, no form marks the cretaceous era in Europe, America, and India, in a more striking manner than the extinct genus Inoceramus (Catillus of Lamk.), the shells of which are distinguished by a fibrous texture, and are often met with in fragments, having, probably, been extremely friable.