Ascending to the next group of rocks, we find the traces of life become more abundant, the number of species extended, and important additions made in certain vestiges of fuci, or sea plants, and of fishes. This group of rocks has been called by English geologists, the Silurian System, because largely developed at the surface of a district of western England, formerly occupied by a people whom the Roman historians call Silures.

p. 61 - Vestiges of the Natural History of Creation (1844)