158 American Se ash ells 



Base of shell with 2 large, smoothish, spiral cords. C. grippi Bartsch and 

 C. pedroana Bartsch are possibly dwarf forms of this species whose beaded 

 sculpture is more variable than is generally suspected. 



Genus Seila A. Adams 1861 



Shell small, very slender, whorls flat-sided, nucleus glassy-smooth and 

 of about 3 whorls. Small, short siphonal canal. Sculpture of strong spiral 

 cords between which lie microscopic axial threads. 



Seila adamsi H. C. Lea Adams' Miniature Cerith 



Plate 2 2t 



Massachusetts to Florida, Texas and the West Indies. 



/4 to /4 inch in length, resembling a miniature Terebra, with about 

 a dozen whorls. Long, slender, flat-sided, dark-brown to light orange-brown 

 in color, and characterized by 3 strong, squarish, spiral cords on each whorl 

 (4 on the last whorl). Occasionally with minute axial threads showing be- 

 tween the spiral cords. Base of shell smoothish, concave. Outer Hp fragile, 

 wavy and sharp. Suture indistinct. This is S. terebralis C. B. Adams. Common 

 from shore to 40 fathoms. 



Seila monterey ensis Bartsch Monterey Miniature Cerith 



Monterey, California, to the Gulf of California. 



% to /4 inch in length, yellowish to reddish brown. Whorls and spire 

 flat-sided. Whorls in spire with 3 raised, flat-topped, evenly spaced, smooth 

 cords between which are numerous, microscopic, axial threads. Last whorl 

 with 5 cords. Base smoothish, concave. Common from low tide to 35 fathoms. 



Genus Alabma Dall 1902 



Shell small, slender. Nucleus slender, of 3 to 4 glassy, smooth whorls. 

 Aperture subcircular. Lower part of the outer lip extended and flaring. 

 Umbilicus very narrow and very small. With obscure, narrow, curved axial 

 ribs and prominent spiral threads. This genus is put in the family Diastomidae 

 by some workers. 



Alabifia tenuisculpta Carpenter Sculptured Alabine 



San Pedro, California, to Lower California. 



/4 inch in length, slender, 8 to 9 whorls, ashen gray with a light-brown 

 undertone. Outer lip thin; umbilicus small. Spiral sculpture of 4 to 6 weak 



