Section 147(2)(b) in Calcutta Improvement Act, 1911
(b)except as the [State Government] may otherwise, by notification, direct, all rules, by-laws, regulations, orders, directions and powers- made, issued or conferred under the portions of the said [Calcutta Municipal Act, 1951], which have been so extended and in force at the date of such extension, shall apply to the said area, in supersession of all corresponding rules, by-laws, regulations, orders, directions and powers (if any) made, issued or conferred under the said Bengal Municipal Act, [1932], or the said Bengal Local Self-Government Act of 1885, as the case may be.