Trunk generally elongated and flattened dorso-ventrally (Fritillarinae-trunk). Endostyle straight or involute at its end. Spiracles in the anterior part of the pharyngeal cavity. Esophagus entering the stomach frontally. Stomach formed by few large cells. Tail rarely longer than the trunk (Fritillaria fraudax; Appendicularinae).
Subfamily Fritillarinae Seeliger, 1895
Subfamily Appendicularinae Lahille, 1888