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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 cerralvoense 
Type locality:—off Cerralvo Island, Gulf of Cal. 
3032 Bittium (Semibittium) Larum 
“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, 
