Sous-embranchement (subphylum) des Rhynchonelliformea  
Classe des Rhynchonellata 
Ordre des Terebratulida 

Sous-ordre des Terebratulidina 
Super-famille des Terebratuloidae 
Super-famille des Dyscolioidae 
Super-famille des Cancellothyroidea 

Genus Cancellothyris Thomson, 1926
[Type species = Terebratula cancellata Koch in Küster, 1843 (p. 35) = Terebratulina hedleyi Finlay, 1927]

Small to medium sized, ovate to subpentagonal, valves biconvex; anterior commissure uniplicate to sulciplicate; surface finely capillate; umbo short, massive, suberect; foramen large, epithyrid, labiate; deltidial plates conjunct. Pedicle collar developed; cardinal process low, bilobed; loop wide, transverse band broad, slightly arched ventrally.
Lophophore plectolophous.

Miocene - Present

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

Extant Species of Cancellothyris
  • C. hedleyi (Finlay, 1927)
  • Diagnosis

    Cancellothyris hedleyi   (Finlay, 1927)

    Type locality: “Westaustralien” [W Australia]
    Depth range: 6 - 366 m

    Terebratula cancellata Koch, in Küster, 1843
    Terebratulina cancellata Davidson, 1886
    Terebratulina hedleyi Finlay, 1927
    Cancellothyris australis Thomson, 1927

    Diagnosis in preparation -


    Should be added:
  • Pedicle characteristics: short, with rootlets radiating from its shaft at the level of the foramen rim; thick outer layer of chitin with long branches or rootlets terminating in holdfasts (both features as in Terebratulina retusa).
  • Muscle disposition: see Fig. in front - dorsal adjustor muscles paired with double attachments to both dorsal valve and pedicle.


    Disposition of the pedicle and pedicles muscles - sagittal section
    (from Richardson, 1979)


    Muscle attachment (from Richardson, 1979)