in natural history, a name by which the echini marini have been lately distinguished. Dr Hill makes them a distinct class of animals living under the defence of shelly coverings formed of one piece, and furnished with a vast number of spines moveable at the creature's pleasure.

CENTUMCELLÆ, (anc. geog.), Trajan's villa in Tuscany, on the coast, three miles from Algaæ; with an excellent port, called Trajanus Portus, (Ptolemy); and a fortifications island at the mouth of the port, made with a huge block of stone, on which two turrets rose, with two entrances into the haven or harbour, Rutillus. Now Civita Vecchia. P. Long. 12. 30. N. Lat. 42.