an arrondissement of the department of the Lower Seine, in France. It is 490 square miles in extent, DIERDORF and contains eight cantons, divided into 292 communes, with a population of 104,207 persons. The chief place is the city of the same name on the Seine, at the mouth of the river Arques. It is fortified on the sea and land sides, and is in the shape of an irregular triangle, whose longest side is towards the sea. It contains 3000 houses, and about 20,000 inhabitants, chiefly dependent on the commerce of the port. Being the best inlet for Paris, it is the great depot for colonial goods, and the resort of foreign ships, especially of those from America. There are many manufactures, but principally of the kind connected with the equipment of ships; and, besides these, some sugar and salt refineries. From this port William the Conqueror sailed with his forces for England. Long. 0° 59', 7' E. Lat. 49° 55' 17' N.