22 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
angle acute; outer lip thin, showing the external markings within; colu¬ 
mella short, very broad at base, oblique, and reflected. One of the cotypes 
measures: length, 10.2; diameter, 3 mm. (Bartsch.) 
Type in United States National Museum. Type locality, Monterey, 
California. 
Cotypes in United States National Museum, No. 15584. Type local¬ 
ity, Monterey, California. 
Range. Vancouver Island, British Columbia, to San Diego, California. 
Fossil, Lower San Pedro Series, Deadman Island, California. 
Bittium attenuatum boreale Bartsch, 1911 
Plate 78, fig. 4 
Proceedings of the United States National Museum, 40:395; PI. 54, fig. 4. 
Shell similar to Bittium attenuatum, but in every way larger and more 
robust. Sculpture very much stronger than in the typical form; the tu¬ 
bercles well-developed on the last whorl but much weaker than on the 
earlier ones. Length, 10.1; diameter, 3.5 mm. (Bartsch.) 
Type in United States National Museum, No. 211586. Type locality, 
Barkley Sound, Vancouver Island. 
Range. Queen Charlotte Islands to Vancouver Island, British Columbia. 
Bittium attenuatum multifilosum Bartsch, 1907 
Plate 78, fig. 3 
Proceedings of the United States National Museum, 33:179. 
Shell similar to Bittium attenuatum, but having seven spiral keels be¬ 
tween the sutures on the whorls of the spire instead of four; that is, a 
strong, intercalated, spiral cord between each of the four primary keels. 
Length, 9.2; diameter, 3 mm. (Bartsch.) 
Type in United States National Museum, No. 127051. Type locality, 
Whites Point, San Pedro, California. 
Range. Monterey to San Pedro, California. 
Bittium attenuatum latifilosum Bartsch, 1911 
Plate 78, fig. 6 
Proceedings of the United States National Museum, 40:395; PI. 54, fig. 6. 
Shell similar to Bittium attenuatum. Whorls a little higher between the 
sutures than in the typical form, with four spiral cords between the sutures, 
which are much broader than in typical attenuatum. The axial ribs are 
strong on the early whorls, but scarcely indicated on the last volutions. 
Shell usually mottled. (Bartsch.) 
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