Some species originally assigned to Hymenocaris were later transferred to Canadaspis, such as Canadaspis perfecta (Hymenocaris perfecta), leaving only Hymenocaris vermicauda.[1] Differences between Hymenocaris and Canadaspis have been used to justify erecting a separate family, Hymenocarididae and order, Hymenostraca for Hymenocaris,[1] although it is also sometimes placed in the family Canadaspididae and the order Canadaspidida.[2]
