This Study as Carried out to descirbe the key to the species of genus Cosmcerca Diesing, 1861. Genus Cosmocera Diesing 1861 is Characterized be presence of plectanes; Oesophagus comprising of cylindrical corpus, an ateriorly differentated phrayngal part an enlongated isthamus and oesophagus bulb; Presence of spicule and gubernaculum number of cloacal papillae; Number of eggs.