1918 Packard: Molluscan Fauna from San Francisco Bay 327 
Blankinship and Keeler (1892) report this species under the name 
of B. filosum, as occurring at the Farallon Islands. That name has 
now been superceded by that of B. eschrichti, which is a northern form 
represented in the southern waters by the variety montereyense. It is 
probable that those authors obtained the variety instead of the typical 
species. 
The same authors list the species B. armillatum Carpenter from 
the Farallon Islands, but that form is now thought to be an extinct 
species. 
Range—wNorthern California to Cape San Lucas, Lower California. 
Bittium subplanulatum Bartsch 
Plate 41, figures 5a and 5b 
Bittium subplanulatum Bartsch (1911), p. 395, pl. 57, fig. 5. 
Description.—This species was originally described by Bartsch (1911) as 
follows: 
‘*Shell broadly elongate-conic, milk white. Nuclear whorls a little more 
than one, well rounded, smooth. The first of the post-nuclear whorls well 
rounded, marked by three spiral cords, one of which is at the summit, another 
on the middle of the whorl, while the third is a little above the suture. The 
succeeding turns show four spiral cords, of which the one at the summit is a 
little less strong than the rest; the remaining three divide the space between 
the sutures into four equal parts. Beginning with the fourth whorl, intercalated 
cords make their appearance between the primary ones, so that on the last 
whorl we have an intercalated cord and sometimes two between all the primary 
cords; these, however, are never quite as strong as the principal ones. In 
addition to the spiral cords, the whorls are marked by decidedly curved, slender, 
well rounded, almost vertical, axial ribs, which are scarcely indicated on the 
first turn, while 14 of them occur upon the second and third, 16 upon the fourth, 
18 upon the fifth and sixth, 22 upon the seventh, 24 upon the eighth, and 26 
upon the penultimate turn. The intersections of the spiral cords and axial ribs 
form weakly developed, rounded tubercles which are truncated on their posterior 
margin, while spaces enclosed between them are very shallow quadrangular 
pits. Sutures strongly constricted. Periphery and base of the last whorl well 
rounded, marked by slender, spiral cords, of which those immediately below the 
periphery are the strongest and are truncated on the posterior margin, sloping 
gently anteriorly. Of these cords, seven occur on the base of the type. <Aper- 
ture rather large, irregularly oval, channeled anteriorly; posterior angle acute; 
outer lip thin, rendered sinuous by the external sculpture; columella decidedly 
oblique, strongly curved, and reflected.’’ 
Length, 7 mm. 
Occurrence.—At station D 5788 (1).* 
The only specimen referred to this species, was dredged by the 
Survey in the vicinity of the Farallon Islands in 68 fathoms from a 
bottom of fine dark green sand. 
Range—San Francisco to Point Loma, California. 
