Thomas Mann was named executive director of the $859 million Kansas City (Mo.) Public School Retirement System effective April 21, said Horace Coleman Jr., chairman of the system board. He replaced Cecelia M. Carter, who left Dec. 31 to lead the $2.1 billion Seattle City Employees Retirement System. Claretha Shumate is serving as interim executive director, Mr. Coleman said. Mr. Mann currently is director of the $6.8 billion Wyoming Retirement System, Cheyenne. Deputy Director Harry Wales will serve as Wyoming interim director starting April 8, Mr. Wales said. Wyomings board will decide April 18 how to find Mr. Manns permanent replacement.