Most of these auxiliary altered steamers have been purchased and refitted for naval service. A number of our ocean mail steamers have been purchased by the Department, such as the Augusta, Florida, Alabama, Quaker City, Keystone State, and State of Georgia; while others have been taken from our rivers flowing into the Atlantic, on which this last class of vessels were formerly plying. In the South Atlantic Squadron are fifteen of this class of transport steamers; fifteen in the North Atlantic; four in the Western Gulf; one in the East Gulf; one in the Brazil, and three in the West India Squadrons. There are also twelve in the Potomac Flotilla; one in the Western Flotilla; two supply steamers; and three in ordinary; with one receiving ship. In the Potomac Flotilla is the captured rebel gunboat Teaser. The De Soto may also be added to this class, carrying 9 guns of 1,600 tons, and at present attached to the Western Gulf Squadron. We now call the attention of the reader to that most formidable class of vessels in our navy, IRON-CLAD STEAMERS--15. The iron-clads of our navy are divided into two classes--the river and ocean steamers, as also steam rams. We will first notice the ocean class: Galena 6 guns, 738 tons. Monitor[6] 3 " 776 " New Ironsides 18 " 3,486 " Roanoke 6 " 3,435 " The Galena and Monitor have been well tested in the present war, but the Galena at present is considered a failure. The New Ironsides, now on special service, is said to be one of the most formidable iron-clad vessels in the world. Of the iron-clad river steamers, we enumerate the following: Benton 16 guns, 1,000 tons. Baron de Kalb 13 " 512 " Cairo 13 " 512 " Cincinnati 13 " 512 " Carondelet 13 " 512 " Essex 7 " 1,000 " Louisville 13 " 468 " Lexington 7 " 500 " Mound City 13 " 512 " Pittsburgh 13 " 512 " Tyler 9 " 600 " The Galena is in the North Atlantic Squadron; the New Ironsides in special service; the Roanoke repairing in New York; and the river iron-clads are attached to the Western Flotilla. IRON-CLAD RAMS--12. General Bragg 2 guns, 700 tons. Gen. Sterling Price - " 400 " General Pillow 2 " 500 " Great Western. - " 800 " Kosciusko - " --- " Lafayette - " 1,000 " Little Rebel 3 " 400 " Lioness - " --- " Monarch - " --- " Queen of the West[7] - " --- " Switzerland - " --- " Simpson - " --- " Six of these rams, though finished, have not received their armament. They are all attached to the Western River Flotilla. Five of these were captured from the rebels, and one was purchased. OTHER VESSELS NOT CLASSED--22.