Characteristics

1. Arms
   1. Hooks present on arms.
      

      Figure. Oral view of half of the arm crown (arms I-IV, arm I at top) of a juvenile M. hamiltoni, 86 mm ML. Drawing from Voss (1980), p. 395.

      

      Figure. Dorsal view of the brachial crown of a large M. hamiltoni. Photograph by Martin Collins.

2. Tentacles
   1. Tentacular club with hooks.
   2. Diagonally set pairs of suckers and pads on distal 2/3 of tentacular stalk.
   
   

   Figure. Oral view of the tentacular club of a large M. hamiltoni. Note the very small marginal suckers. Photograph by Martin Collins.
3. Funnel
   1. Funnel valve absent.
   2. Funnel organ: Dorsal pad with three papillae.
      
      
4. Mantle
   1. Tubercles absent in adults, present in paralarvae and juveniles.
      
      
5. Fins
   1. Fins ovate, without anterior lobes.
   2. Fins terminal.
      
      
6. Photophores
   1. Two ocular photophores: crescent-shaped photogenic region in medial photophore and small, oblong photogenic region in lateral photophore within concavity of first.
   2. Arm tip photophores probably absent.

Comments

This is the only cranchiid that has hooks on the arms. Characteristics are from Voss (1980).