Whenever it is necessary because of lack of work, lack of funds, or whenever it is advisable in the interest of economy to reduce the staff of any department or agency of the counties, or any municipality affected by this part, the appointing authorities shall lay off employees according to the procedure set forth in this part and the rules and regulations prescribed thereunder. The duties performed by the employee or employees so laid off may be assigned to any other permanent civil service employee or employees in the department or office, who, in the opinion of the director of personnel, are qualified to perform such duties regardless of the specific classification or grade to which such employees are allocated. Layoffs shall be made by laying off the employee in the classification to be affected by the layoff who last attained such classification or grade, and so on in succession. In case there are two or more who would be affected by a layoff, and who have an equal rating as to seniority, the employee who stands lowest according to the efficiency records kept by the director of personnel shall be laid off. When an employee is laid off in a department which has other classifications or grades lower than the classification or grade from which he, or she, is laid off, he, or she, shall have the option of working in any other lower classification or grade in the same department, provided the director of personnel finds that he, or she, is qualified to perform the duties of such lower classification or grade, such option being subject, however, to the following limitation. Where an employee so laid off elects to drop to a lower classification or grade, and where the appointing authority reduces the number of employees in such lower classification or grade, the reduction shall be made in the manner in which it is herein provided layoffs shall be made, except that such reduction shall in no case cause the layoff of any permanent employee in such lower classification or grade who has more seniority in the department than the employee laid off from the higher classification or grade. A person laid off from a classification or grade shall have the right, so long as he, or she, is in the service or on the layoff list to return to the position from which he, or she, is laid off, in the event such position is refilled. The names of employees laid off as provided herein shall be placed upon the department layoff list for such position as in the opinion of the director of personnel the employees are qualified and entitled to hold, including any positions which may be thereafter created in the department. The order of the names on the layoff list shall be in the relative order of seniority; provided, however, that where there are two or more employees who are equal in seniority they shall stand on the layoff list in the order of their efficiency records kept by the director of personnel. All permanent employees in the classified service compensated on a monthly basis who are to be laid off are to be given 15 days’ notice of such layoff prior to the effective date thereof.