(Johnston, 1828-29)
Description:
Procephalothrix filiformis is up to about 15 cm long and 1 mm or
more wide. The long bluntly pointed head is generally white or translucent, the remainder of the body a yellowish-white to orange colour which is often darker in the posterior half of the body.
Anatomically very similar to species of the genus Cephalothrix , Procephalothrix filiformis can be distinguished by the way it contracts in a tight spiral when disturbed. Internally the inner circular muscle fibres associated with the foregut region separate the species from members of the genus Cephalothrix . There is no nerve layer present between the epidermal basement membrane and the outer body wall circular muscle layer. Sexually mature specimens have been found in February.
Habitat:
The species is found beneath stones in muddy areas or buried in muddy gravel from the mid-shore level down to depths of 40 m or more.
Distribution:
The geographic distribution is restricted to the British Isles and the coast of France.