download pdf

282 American Seashells
^ to % inch in length, moderately solid, oblong but more constricted
at the upper portions. Spire of 5 whorls, elevated, pointed and with a tiny,
pimple-like nucleus (usually eroded in northern specimens) . Suture narrowly
and deeply channeled. Body whorl swollen at the lower half. With numer-
ous microscopic, wavy, incised spiral lines. Color yellowish, sometimes with
numerous golden-yellow, fine spiral lines. Columella is a single, raised spiral
cord. Common in shallow water. A. cerealis Gould is probaby the same
species.
Genus Cylichna Loven 1846
Cylichna gouldi Couthouy Gould's Barrel-bubble
Massachusetts Bay to off Cape Cod. Arctic Seas.
Plate 26r
% inch (9 mm.) in length, fragile, chubby, with the spire usually sunk
in and consisting of 4 or 5 whorls. Color dirty-white with a yellowish
periostracum. The whorls are much more globose and the anterior end
more constricted than in the much smaller species, Retiisa ohtusa. Formerly
placed in the genus Retusa. Uncommon from 26 to 34 fathoms.
Cylichna alba Brown Brown's Barrel-bubble
Arctic Seas to North Carolina. Bering Sea to San Diego, California.
/4 inch (5 mm.) in length, fragile, narrowly oblong with flat sides.
Apex with a dished, shallow depression. Upper 73 of aperture narrow;
below it is wide. Columella short, rounded, slightly raised. Shell white,
smoothish, except for microscopic, spiral scratches. Periostracum thin,
shiny, yellowish, but often darkly stained with brown. Commonly dredged
from I to 1000 fathoms in cold water.
Subgenus Cylichnella Gabb 1872
Cylichna bidentata Orbigny Orbigny's Barrel-bubble
North Carolina, Florida to Texas and West Indies.
Plate 26q
3 mm. in length, somewhat resembling alba, but its columella has a spiral,
callous fold and an indistinct nodule below. The shell is more oval. Glossy-
white. Commonly found from shallow water to 200 fathoms. This is C.
biplicata of authors, not A. Adams.
Fa77nly PHILINIDAE
Related to the Scaphander Canoe-shells, but different in having the