The Ascarididae are a family of the large intestinal roundworms. Members of the family are intestinal parasites, infecting all classes of vertebrates. It includes a number of genera, the most well known of which are: * * * Ascaris * † (fossil) * Baylisascaris * * * Hexametra * * * Parascaris * * * Toxascaris * Toxocara * Ascaris lumbricoides is the main ascarid parasite of humans, causing ascariasis.