(McIntosh, 1873-74)
Description:
A moderately long and slender species: up to 15 cm long and 0.5-1.0 mm wide. The head is flattened and rather spatulate. The body tapers posteriorly. It produces copious amounts of viscid mucus and readily forms delicate tubes to which sand grains adhere.
Most specimens are an overall pure milky-white, although the intestinal regions may be faintly tinged orange-brown or yellowish-brown. The posterior body margins are often translucent. In the head, which may also appear translucent or exhibit a faint reddish tint, the rhynchodaeum is sometimes distinguishable as a median white line in front of the cerebral ganglia. The body wall with dorsal and ventral muscle crosses. Lateral sensory organs are present. Cephalic glands are absent.
Habitat:
A lower littoral to shallow water species. Found borrowed in clean sand or among sand-binding algae, sometimes associated with polychaetes of the genus Magelona .
Distribution:
Apart from the British Isles the species has been found on the French and Italian coasts.