The Bathyal Holothurians of the New Zealand Region
[Introduction]
Diagnosis : Tentacle ampullae lacking. Respiratory trees usually not connected with a rete mirabile. Stone canal usually in connection with the bodywall, sometimes opening outwards through the bodywall. No Cuvierian organs. Deposits tables; C-shaped bodies may be present and, very rarely, buttons. (After Mortensen, 1927.)
Remarks: This family is cosmopolitan, comprising mainly deepsea forms. Approximately fifteen genera are recognised at the present time, of which two, Bathyplotes Östergren and Mesothuria Ludwig, are known from the New Zealand region. The genera may be readily distinguished as follows:
1 (2) | Gonad composed of a single tuft; deposits tables with approximately circular discs bearing large perforations | Mesothuria (p. 18) |
2 (1) | Gonad composed of two tufts; deposits tables with cross-shaped discs | Bathyplotes (p. 15) |