Amphibrachium grows in the tissues of a sponge, Euplectella, and protrudes its hydranth into the canal-system of the sponge; and Lar grows on the tubes of the worm Sabella.
11) grows upon the tubes of the worm Sabella and produces a medusa known as Willia.
The plasma is coloured red by haemoglobin: it is sometimes (in Sabella and a few other Polychaeta) green, which tint is due to another respiratory pigment.
- Sabella vesiculosa, Mont.
(d) Univalvia absque spira regulari: Patella, Dentalium, Serpula, Teredo, Sabella.