Page:American Seashells (1954).djvu/363

Rh 3 to 4 mm. in length, fragile, translucent-white, spindle-shaped, with a sharp, long, spike-like apex. Glossy and with 4 or 5 very fine, indistinct, punctate, spiral lines at each end. Outer lip thin, following the curvature of the body whorl to just below the middle where it continues in a straight line. Umbilicus chink-like. Periostracum thin and pale-straw. Common from 5 to 100 fathoms. R. bushi Dall comes from deep water off North Carolina. It is larger, with a long apical process and with a long, chink-like umbilicus. The genus Volvulella Newton 1891 is Rhizoriis. Rhizorus acutus Orbigny Spined Spindle-bubble Plate 26I North Carolina to southeast Florida and the West Indies. 2 to 3 mm. in length, spindle-shaped, rather oblong, fragile, except for minute spiral lines at each end. Upper end of aperture ends in a very sharp, rather prolonged spike. Umbilicus rarely, if ever, present. Commonly dredged down to 150 fathoms. R. 7ni?iutus Bush is probably the young. R. aspinosiis Dall from the same region has the process poorly developed, and may be a form of this species. Fantily SCAPHANDRIDAE Genus Scaphander Montfort 18 10 Scaphander piinctostriatus Mighels Giant Canoe-bubble Plate 26-0 Arctic Seas to Florida and the West Indies. I to 1% inches in length, very lightweight, but moderately strong. Ovate-oblong. Apex with a slightly sunken area. Aperture constricted above, roundly open below. Columella simple, rounded. Shell smoothish, except for numerous, spiral rows of microscopic, elongate punctations. Color chalk-white, with a straw periostracum. Fairly common from 20 to 1000 fathoms. Scaphander 720 bills ^errill (Noble Canoe-bubble) from off New Eng- land is the same size or smaller, has a proportionately much larger aperture, its outer lip is wing-like above, and the microscopic punctations are round. It is uncommon. A figure of S. luatsoni Dall is on plate 26m. Family ACTEOCINIDAE Genus Acteocina Gray 1847 Acteoci'ua culitella Gould Western Barrel-bubble Kodiak Island, Alaska, to Lower California.