414 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 39. 



der thread at the summit. In addition to these spiral cords, the 

 whorls are marked by well-rounded, slender, somewhat retractive axial 

 riblets, which, like the spiral sculpture, become obsolete on the last 

 volution. Of these riblets, 22 appear upon the second and third, 

 24 upon the fourth and fifth, and about 40 upon the last volution. 

 Sutures constricted ; periphery of the last whorl marked by a broad, 

 shallow sulcus. Base somewhat inflated, well rounded, marked by 

 6 low, rounded, subequal and subequally spaced spiral keels. Ante- 

 rior portion of the base surrounding the umbilical area smooth, 

 excepting slender lines of growth. Aperture broadly ovate, some- 

 what effuse anteriorly; posterior angle acute; outer lip thin, showing 

 the external sculpture within; columella slender, strongly curved, 

 and very slightly re volute. 



The type (Cat. no. 105515, U.S.N.M.) has 7 post-nuclear whorls, 

 and measures: Length 4 mm., diameter 1.7 mm. It comes from San 

 Ignacio Lagoon, Lower California. 



ALABINA CALIFORNICA Dall and Bartsch. 



Plate 62, fig. 7. 



Bittium (Elachista) calif ornicwn Dall and Bartsch, Nautilus, vol. 15, 1901, 

 pp. 58-59. 



Shell elongate-conic, yellowish white. Nuclear whorls 2tV, moder- 

 ately rounded, smooth. Post-nuclear whorls strongly rounded, 

 somewhat inflated, appressed at the summit, marked by broad, 

 low, strong, protractive axial ribs of which 14 occur upon the first 

 to third, 16 upon the fourth, and 18 upon the penultimate whorl. 

 In addition to the axial ribs, the whorls are marked on the spire 

 by three feebly impressed, spiral lines which pass over the ribs as 

 well as the broad, intercostal spaces. The middle one of these 

 three lines is halfway between the sutures. The other two divide 

 the space anterior and posterior to it into equal halves. Sutures 

 strongly constricted. Periphery and base of the last whorl well 

 rounded, smooth, excepting faint lines of growth. Aperture broadly 

 ovate; posterior angle acute; outer lip thin; columella short, moder- 

 ately strong, strongly curved and slightly reflected over the 

 reinforcing base. 



The type has 8 whorls and measures: Length 5.3 mm., diameter 

 2.2 mm. It is one of 7 specimens (Cat. no. 162548, U.S.N.M.) and 

 came from Dead Man's Island, San Pedro, California. Cat. no. 

 162547, U.S.N.M., one specimen, came from the Lower San Pedro 

 Series, Dead Man's Island, California; and Cat. no. 195215, U.S.N.M., 

 75 specimens, came from the same locality. 



