TROCHIDAE 107 



ally with a black-spotted edge and with a thickened central callus which is 

 light-brown to black. A. albicosta C. B. Adams and A. fungoides Roding are 

 the same. Moderately common in the West Indies, occasionally found on the 

 Lower Florida Keys. 



Fajnily LEPETIDAE 

 Genus Lepeta Gray 1842 



Small, flattish, uncoiled shells which are "hat-shaped," similar to Acmaea, 

 but the embryonic nucleus is spiral; the animal has no external gills and the 

 proboscis is produced into a labial process on each side. The radula has a 

 median tooth, which in Acmaea is absent. 



Lepeta caeca Miiller Northern Blind Limpet 



Plate 17J 



Arctic Seas to Cape Cod, Massachusetts. 



Va: to Y2 inch in maximum diameter, moderately conic, with straight 

 sides, oval-elongate in outline. Rather fragile, dull-white to brownish exter- 

 nally and with fine, granulose, crowded, radial threads. Interior white or 

 tinged with pink. Apex usually eroded. A common cold-water species often 

 dredged in shallow water off New England. 



Superb amily TROCHACEA 



Faiitily TROCHIDAE (Top Shells) 



Subfaimly MARGARITINAE 



Genus Margarites Gray 1847 



Subgenus Margarites s. str. 



Margarites costalts Gould Northern Rosy Margarite 



Plate lyt 



Greenland to Cape Cod, Massachusetts. Bering Strait to Port Etches, 

 Alaska. 



% to % inch in length, a little wider, with 5 evenly and well-rounded 

 whorls. Narrowly and deeply umbilicate. Angle of spire about 90 degrees. 

 Next to last whorl with i o to 12 smoothish, raised, spiral threads. Columella 

 and outer lip thin, sharp, the latter finely crenulate. Color rosy to grayish 

 cream. White within the smoothish umbilicus. Aperture pearly-rose. Com- 

 monly dredged from lo to 62 fathoms. M. groenlandiciis Moller is the same. 

 Formerly known as M. cinereus Couthouy. 



