Definition of "testacea"

ANAIMONA, Aquatilia Exanguia, Bloodless Fishes, are divided into Mollia Soft Fishes without Shells; Crustata, those that are covered with thin pliant Shells; and Testacea, those which have thick, hard brittle Shells.

1722, John Jones (tr.), Oppian's Halieuticks of the Nature of Fishes and Fishing of the Ancients, page 231

The echinite family […] may be deemed characteristic of the chalk formation, affording of itself as many shells as the other testacea do.

1829, Andrew Ure, A New System of Geology, page 285

[…] to fancy, for example, that the testacea of the ocean existed first, until some of them, by gradual evolution, were improved into those inhabiting the land.

1832, Charles Lyell, chapter I, in Principles of Geology […] , volume II, London: John Murray, page 11