Trachylinae
（重定向自Trachylina）
Trachylinae (also Trachylina, Trachylinida, etc.) are a cnidarian subclass of the Hydrozoa. They are placed at order rank in many older classifications, and limited to contain the Narcomedusae and Trachymedusae. But the Actinulidae, then considered an independent order, and probably also the Limnomedusae which were traditionally placed in the paraphyletic "Hydroida", belong to this group too. It is not entirely clear whether the Limnomedusae and the Trachymedusae as conventionally circumscribed are monophyletic