Sous-embranchement (subphylum) des Rhynchonelliformea
Classe des Rhynchonellata
Ordre des Terebratulida
Sous-Ordre des Terebratellidina
Super-famille des Megathyridoidea


Genus Fallax Atkins, 1960
[Type species= Fallax dalliniformis Atkins, 1960 (p. 72)]

Medium, biconvex, smooth, elongate ovate to subpentagonal, anterior commissure rectimarginate to parasulcate; beak low, erect; beak ridges rounded; deltidial plates conjunct in adults; foramen small, round, permesothyrid. Dental plates lamellar, straight; pedicle collar broad, sessile, impunctate. Cardinalia lamellar with short, well-developed septalium; inner and outer hinge plates well developed, crural bases not differentiated; cardinal process not differentiated; median septum extending anteriorly about three-quarters valve length; crura short, subparallel, crural processes short; loop diploform; lophophore and mantle finely spiculate.


Diagnosis from volume 5 of the
Treatise on Invertebrate Paleontology (2006)

Extant Species of Fallax
  • F. dalliniformis Atkins, 1960
  • F. antarcticus Foster, 1974
  • F. neocaledonensis Laurin, 1997
  • Laurinia neocaledonensis Zezina 2005


    Fallax antarcticus   Foster, 1974

    Type locality: “HU st. 27-35 (62°47'S, 158°12'W): 2288-2342 m.”
    Depth range: 2285 - 2342 m

    Diagnosis in preparation -