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 



Plate 26r 



Massachusetts Bay to off Cape Cod. Arctic Seas. 



% 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 



Plate 26q 



North Carolina, Florida to Texas and West Indies. 



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 



