(Montagu, 1803)
Description (shell):
The shell is internal, covered over by the mantle, up to 5 mm in length, oval, frail, semi-transparent, glossy, whitish. The aperture is not quite as long as the spire. The sculpture consists of spiral rows of regular indentations, linked in chain-fashion, approximately 10 rows per mm (P. catena-drawing ).
Animal:
The body may reach 7 mm in overall length, cream or pale brown in colour, with tiny specks of dark brown, orange and white, the dark brown being present only on the dorsal surface. The overall shape is elongated and slender. Cephalic disc not indented anteriorly; mantle cavity not gaping posteriorly, extending only a short distance beyond the metapodium.
Habitat:
This uncommon species may occur under boulders on British shores, but is rather more prevalent offshore. The natural diet is not known, but this philinid is known to be itself eaten by flatfish.
Distribution:
It has been reported from Lofoten to the Mediterranean Sea and the Canary Islands, to 2000 m in depth (Distr. P. catena).