168 American Seashells 



more than H the length of the shell. Periostracum thick, brown and with 

 long spicules over the region of the cords. Commonly dredged in cold, 

 shallow water. 



Trichotropis bicarinata Sowerby Two-keeled Hairy-shell 



Plate 24a 



Arctic Ocean to Alaska. Arctic Ocean to Newfoundland. 



I % inches in length, equally wide, with about 4 whorls. Characterized 

 by 2 strong, spiral carinae at the periphery, by the wide, flattened columella 

 and by the flaky, brown periostracum which is grossly spinose on the carinae. 

 Uncommon just ofl^shore in cold water. 



Trichotropis insignis Middendorfl^ Gray Hairy-shell 



Plate 24c 



Alaska to northern Japan. 



I inch in length, similar to T. bicarinata but smaller, with a much heavier 

 shell, weakly carinate with other numerous, uneven, spiral threads, and with 

 a thin, grayish periostracum. Both this species and bicarinata are easily distin- 

 guished from the more common cancellata by their much shorter spires and 

 large flaring apertures. Uncommon just offshore. 



Family CAPULIDAE 

 Genus Capulus Montfort 18 10 

 Subgenus Krebsia Morch 1877 



Capulus incurvatus Gmelin Incurved Cap-shell 



North Carolina to southeast Florida and the West Indies. 



% inch in size, cap-shaped, white to cream, and with a very large, cir- 

 cular to slightly oval aperture, i /4 to 2 whorls. Spire small, usually tightly 

 coiled, but sometimes partially free. Early whorls usually with small spiral 

 cords, but these are frequently worn smooth. Sculpture of small, irregular, 

 rounded growth lines which are crossed by numerous spiral cords which 

 may be rounded or sharp. Periostracum thick, light-brown, with spirally ar- 

 ranged rows of small tufts. Muscle scar within the aperture is horseshoe- 

 shaped with the swollen end just inside the columella. Uncommon on rocks 

 just below low water. I believe that C intortus Lamarck is merely a variant 

 of this species. Compare with Hipponix antiquata which is much heavier, 

 lacks the spiral cords and is more coarsely sculptured. 



Capulus calif ornicus Dall Californian Cap-shell 



Redondo Beach to Lower California. 



