Maa Siddhidatri would be the ninth avatar of maa Durga and is worshipped on the ninth day of navratri. Ma Siddhidatri is represented with four arms sitting down on a good looking lotus flower. Throughout the 1st 9 times, nine facets of Durga often called Navadurga are meditated upon, one https://www.youtube.com/watch?v=S1HpMpEww4Q