The cashier of each bank and the secretary or clerk of each incorporated railroad, canal or turnpike company shall, on the first Monday of October in each year, or within 15 days previous thereto, make a return to the state treasurer, verified by his oath, stating the amount of capital stock of such bank or railroad, canal or turnpike company then actually paid in, and in default thereof, the whole capital stock mentioned in the act of incorporation of such bank or company shall, for the purpose of computing the state tax payable by such bank or company, be deemed to have been paid in.