From North Mississippi.
Demopolis, March 7.
--A dispatch to Gen. Jackson, dated Canton, March 2d, says the enemy's army, with the 16th and 17th corps, and between 25,000 and 30,000 infantry, and 1,500 cavalry, left Canton that morning, after remaining three days. Sherman reached there the 28th, remained six hours, and then pushed on to Vicksburg, leaving McPherson in command.
He sent back nine couriers in great haste to McPherson on the 29th, urging him to hasten to Vicksburg, via Livingston and Brookville.
A large number of empty transports passed down the river to Vicksburg, said to be for the purpose of taking Sherman's army up the river.
The enemy destroyed the railroad eight miles below Canton, and in the country burned houses and destroyed provisions.
Over 200 of the enemy were killed or captured.--Ross killed 35 out of 70 negro cavalry near Yazoo City.
Several wagon trains were also taken.
The enemy destroyed no railroad bridges.
Cyphered dispatches were captured from the enemy's couriers.
Transports are going down the Yazoo river. 