in Natural History, a name by which the echini marini have been 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, in Ancient Geography, Trajan's villa in Tuscany, on the coast, three miles from Algeæ; with an excellent port, called Trajanus Portus, (Ptolemy); and a factitious island at the mouth of the port, made with a huge block of stone, on which two turrets rose, with two entrances into the basin or harbour, (Rutilius). Now Civita Vecchia. E. Long. 12° 30'. N. Lat. 42°.