an arrondissement of the department of the Ain, in France, 310 square miles in extent. It comprehends six cantons, divided into sixty-one communes, and contains 51,500 inhabitants. The capital is the city of the same name, situated in a narrow valley between two mountains, on the border of the lake of Nantua. It has 340 houses, and 3860 inhabitants, who carry on several tanneries, paper and silk mills, and make hats and cotton goods. Long. 5. 33. E. Lat. 46. 8. N.