(Giard, 1904)
Description:
Body thin, long and thread-like. Borders of segments difficult to recognize. Each segment with tufts of sensory cilia in posterior half, and three pairs of adhesive organs: a ventral, dorsal and lateral pair, the latter formed by a group of 6-10 glands, sometimes more. Pygidial lobes not wider than posterior part of trunk, simply rounded with paired subterminal groups of ventral adhesive glands. Bacillary glands and other epidermal glands present.
Segments 6-9 are fertile. Females never with more than two oocytes per segment at a time. Males with one pair of spermioducts in each fertile segment.
Size:
Up to 4 mm for about 15 segments.
Colour:
Transparent, with striking, refringent, greenish yellow epidermal glands, more or less irregularly distributed in the entire epidermis and concentrated in two bands on both sides of ventral ciliated groove.
Habitat:
Relatively clean sandy sediments of medium grain size; surface layers of intertidal sand flats.
Distribution:
North Sea (Sylt, Amrum, Helgoland Dune, Dutch and Belgian coast, east coast of England), English Channel (Ambleteuse, Roscoff area), Irish Sea (Northern Ireland, North Wales).