animals, they form a section of the Trachelipods, which he calls carnivorous. (Zoophages.) In the other section of Trachelipods, which he calls herbivorous (Phytiphages) the aperture of the shell is entire, and the animals have, jaws formed for feeding on vegetables.
Mr. Dillwyn further asserts, that every fossil Turbinated Univalve of the older beds, from the Transition lime to the Lias, belongs to the herbivorous genera; and that the herbivorous class extends through every stratum in the entire series of geological formations, and still retains its place among the inhabitants of our existing seas. On the other hand, the shells of marine carnivorous Univalves are very abundant in the Tertiary strata above the Chalk, but are extremely rare in the Secondary strata, from the Chalk downwards to the Inferior oolite; beneath which no trace of them has yet been found.
Most collectors have seen upon the sea shore numbers of dead shells, in which small circular holes have been bored by the predaceous tribes, for the purpose of feeding upon the bodies of the animals contained within them a similar holes occur in many fossil shells of the Tertiary strata, wherein the shells of carnivorous Trachelipods also abound; but perforations of this kind are extremely rare in the fossil shells of any older formation. In the Green-sand and Oolite, they have been noticed only in those few cases where they are accompanied by the shells of equally rare carnivorous Mollusks; and in the Lias, and strata below it, there are neither perforations, nor any shells having the notched mouth peculiar to perforating carnivorous species.
It should seem, from these facts, that in the economy of
submarine life, the great family of carnivorous Trachelipods,
performed the same necessary office during the Tertiary
period, which is allotted to them in the present ocean. We
dicate their molluscous inhabitant to have been carnivorous, an entire aperture does not always indicate an herbivorous character.
