Medium-sized shell (42.5-90.0 mm) with about 9-11 convex whorls, surrounded by a weak subsutural concavity. Suture appressed to preceding whorl, not incised.
Protoconch broken or eroded in all examined specimens and therefore unknown.
Eight or nine rather strong and narrow axial ribs, reaching from suture to suture and separated by narrow and not very deep impressed interspaces on the 2 uppermost teleoconch whorls. On the following 2 or 3 whorls the number of ribs increases up to 11-13 per whorl, becoming somewhat broader and lower and usually stopping below the upper suture; interspaces between ribs become shallower and less distinct. On antepenultimate or penultimate whorl the axial ribs become very low and less distinct and the spacing becomes irregular. Axial ribs always obsolete on body whorl and usually also on penultimate whorl.
Teleoconch begins with 5 or 6 strong but low and rounded spiral cords. Starting with the second or third whorl an additional clearly finer spiral cord appears just below suture, and a fine intercalated spiral thread appears between each pair of cords. On the following whorls the number of fine spiral threads increases by intercalation; up to 5 or 6 between each pair of primary cords on body whorl. In the subsutural concavity only some fine threads. The spiral sculpture is crossed by rather strong and well-visible curved growth lines, giving the surface of the shell the texture of linen.
Aperture ovate, whitish to yellowish in colour, acute at posterior end. Parietal
callus thin, smooth and glossy, appressed to lower part of body whorl. Columellar folds absent. Outer lip simple and thin, sculptured with numerous fine internal lirae; outline of lip strikingly curved like an elongated reversed 'S'. Siphonal canal shorter than aperture length, conspicuously curved. Outer side ornamented with numerous fine, low and regularly spaced spiral cords which are intercalated by numerous fine spiral threads.
Operculum corneous, colour pale reddish brown, thin, shape and size corresponding to aperture. Outer side with fine concentric growth lines. Typical of genus, with terminal nucleus.
Periostracum thin, olive-green, not hairy.
Radula typical of genus. Central tooth nearly rectangular, tricuspid, median cusp somewhat stronger. Lateral teeth strongly curved, with 6 or 7 long, strong and pointed cusps; outermost one much larger than all others. At both ends of lateral tooth with a small denticle.

Comparing both the holotypes of F. graciliformis and F. sieboldi shows, that the latter is doubtless a junior synonym. Both holotypes are nearly identical in size, shape, sculpture and both were found in Japan. F. valdiviae appears to be conspecific, the description based on subadult East African specimens. HADORN AND FRAUSSEN (1999) compared F. valdiviae with F. westralis (described in this paper) misidentified in the 1999 paper as F. chrysodomoides. After examination of the holotype of F. graciliformis and other mate¬rial mainly from the Philippines we treat the conchologically not distinguishable F. valdiviae from East Africa provisionally as a junior synonym of F. graciliformis. Further study can reveal a subspecific status for F. valdiviae. The radula of F. graciliformis is still unknown, the radula of F. valdiviae was figured by HADORN AND FRAUSSEN (1999).
F. hyphalus differs from F. graciliformis by having a more slender spire tip, a smaller adult size, a thinner and lighter shell, and by the less convex whorls.

Range and habitat: Japan (Boso peninsula and southwards), East China Sea, Philippines, South China Sea (HIGO ET AL., 1999: 263), and along the East African coast, from the Gulf of Aden, Djibouti, Somalia (HADORN AND FRAUSSEN, 1999: 120) to southwestern Madagascar. Between 50 and 1134 m deep, on sandy bottom.