THYROSTRACA, an order of Crustacea, comprising barnacles, acorn shells and some allied degenerate parasites.
Xxiv., p. 55) added a new species to Plumulites (Barrande, 1872), remarking that the species in question, P. devonicus, " is interesting in being the first representative of fossil barnacles from the Devonian, Barrande's species of Plumulites and Anatifopsis, as well as the Turrilepis of Woodward, being from the Upper and Lower Silurian, and Plumulites jamesi (Hall and Whitf., Pal.
The horizontal distribution of barnacles over all seas is fully explained by Darwin.
Originally, the name was given to the stalked barnacles (Lepadidae of C. Darwin), which attach themselves in great numbers to drift-wood and other objects floating in the sea and are one of the chief agents in the fouling of ships' bottoms during long voyages.
Acasta sulcata, Lamk., in the scientific study of zoology had replaced the fabulous tales of medieval writers, it was a long time before the true affinities of the barnacles were appreciated, and they were at first classed with the Mollusca, some of which they closely resemble in external appearance.