Haecker
Diagnosis: Shell laterally compressed, butterfly-shaped. Galea large, convex, inflated, broadly triangular in oral and aboral views. Valves small, covered by aboral surface of galea. Rhinocanna long, thin, tubular, very near oral margin of valve. Irregular margin around nasal opening of rhinocanna, latter with frenulum. Nasal tubes branch at obtuse angles, with anchor threads. Anchor threads bidentate, with terminal ends arranged like picks with few short, opposing, subterminal teeth. Terminal branches of all tubes with strong, irregular thorns.
Length of nasal tubes: 2.0-2.2 mm.