ACTEOCINIDAE 281 



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. 



