CREATE TABLE table_24964 ("No." FLOAT, "Season" TEXT, "Championship" FLOAT, "No. of teams" FLOAT, "Start  ( reg. season ) " TEXT, "Finish  ( incl. championship ) " TEXT, "Top record" TEXT, "National Champion" TEXT)

What season ended on April 18?
SELECT "Season" FROM table_24964 WHERE "Finish (incl. championship)" = 'April 18'
SELECT "Season" FROM "table_24964" WHERE "Finish (incl. championship)" = 'April 18'