197 



one-half, marked by two slender threads which divide the space 

 between the sutures into three equal parts. Post-nuclear whorls 

 strongly shouldered at the summit, marked by three strong spiral 

 keels which divide the space between the sutures into four almost 

 equal parts. The space between the first of these keels below the 

 summit and the summit is a little narrower than the rest. In 

 addition to these three strong spiral keels, intercalated keels are 

 present, the first of which is at the summit, while another occurs 

 between each of the other keels. On the last whorl these attain 

 a strength almost equal to that of the primary keels. In addition 

 to this spiral sculpture, the whorls are marked by well-developed, 

 slightly retractive, axial ribs, of which 14 occur upon the first and 

 second, 15 upon the third, 16 upon the fourth, 18 upon the fifth 

 and sixth, 20 upon the seventh, 22 upon the eighth, 28 upon the 

 ninth and tenth, and 34 upon the penultimate turn. The intersec- 

 tions of the axial ribs and the spiral keels form strong cusps which 

 are suddenly truncated posteriorly and slope gently anteriorly 

 the spaces inclosed between them being small, rounded pits. Su- 

 tures channeled. Periphery of the last whorl marked by a slen- 

 der cord. Base moderately prolonged, ornamented by six spiral 

 cords, of which the two immediately anterior to the periphery and 

 the two at the base of the columella are decidedly stronger than 

 the rest. Aperture rather large, channeled anteriorly; columella 

 stout, twisted, somewhat revolute, and reflected; parietal wall 

 glazed with a moderately thick callus." — Bartsch. 

 Type locality: — Deadmans Island, California. 



3029 Bittium asperum Gabb. 



Type locality: — Lower Pleistocene, Santa Barbara, Cal. 



3030 Variety Lomaense 



Type locality: — off Point Loma, Cal. 



3031 Bittium eerralvoense 



Type locality: — off Cerralvo Island, Gulf of Cal. 



3032 Bittium (Semibittium) Latum 



"Shell very regularly elongate-conic, light brown. Nuclear 

 whorls at least two, worn. Post-nuclear whorls appressed at the 

 summit, decidedly overhanging. The early post nuclear whorls 

 are marked by four equal and equally spaced spiral cords, the first 

 of which is at the summit; these cords divide the space between 

 the sutures into four equal parts. On the sixth whorl intercalated 

 spiral cords make their appearance in the middle, between all the 

 primary cords; these attain a little more than half the strength 

 of the primary cords on the last turn. In addition to the spiral 

 sculpture, the whorls are marked by moderately strong, almost 

 vertical, axial ribs, of which 14 occur upon all but the penultimate 

 turn, which has 18. The intersections of the axial ribs and spiral 

 cords form elongate tubercles, which have their long axis parallel 

 with the spiral sculpture. The spaces inclosed between the axial 

 ribs and the spiral cords are rectangular pits on the early whorls 

 and broad, incised lines on the later ones. Sutures slightly con- 

 stricted. Periphery of the last whorl angulated, marked by a 

 spiral cord. Base short, slightly concave in the middle, marked 

 by six spiral cords which grow successively from the periphery to 

 the umbilical region. In addition to the above sculpture, the 

 entire surface of spire and base is marked by fine lines of growth 

 and exceedingly fine, spiral striations. Aperture quadrangular, 

 channeled anteriorly; posterior angle obtuse; outer lip thin, 

 showing the external sculpture within, rendered sinuous at the 

 edge by the external sculpture; columella moderately strong, 



