CLASS GASTROPODA 
155 
Subgenus Chrysallida Carpenter, 1856 
Odostomia astricta Dali and Bartsch, 1907 
Plate 57, fig. 1 
Proceedings of the United States National Museum, 33:514; PL 46, fig. 1. 
Shell elongate-conic, bluish-white. Nuclear whorls decollated. Post- 
nuclear whorls very slightly rounded, separated by deeply channeled 
sutures. In this species the vertical ribs exceed the four spiral keels in 
strength, their junction forming elongated tubercles, the long axis of which 
coincides with the spiral keels. The vertical ribs, of which there are 
sixteen upon all of the turns, slant decidedly backward toward the aperture. 
They are rather distantly spaced and the spaces inclosed between them 
and the spiral keels are deep oblong pits, the long axis of which coincides 
with the spiral sculpture. Periphery of the last whorl marked by a deep, 
wide channel across which the ribs extend feebly to the first subperipheral 
keel. Base rather long and well-rounded, marked by seven, rather narrow, 
slender, spiral keels, which successively decrease in strength from the 
periphery to the umbilical area, the anterior ones being only faintly indi¬ 
cated ; the spaces which separate the keels are about twice as wide as the 
keels and are crossed by many very slender raised vertical threads. Aper¬ 
ture oval, outer lip rather thick, columella twisted, re-enforced by the 
attenuated base and provided with a moderately strong fold at its inser¬ 
tion; parietal wall covered by a strong callus. Length, 2.9; diameter, 
1.2 mm. (Dali and Bartsch.) 
Type in United States National Museum, No. 196280. Type locality, 
Monterey, California. 
Range. Known only from type locality. 
Odostomia cooperi Dali and Bartsch, 1907 
Plate 57, fig. 7 
Proceedings of the United States National Museum, 33:514; PI. 46, fig. 7. 
Shell broadly conic, white. Nuclear whorls smooth, largely obliquely 
immersed in the first of the succeeding turns above which only about half 
of the last turn projects. Post-nuclear whorl moderately rounded, slop- 
ingly shouldered at the summit, the shoulder bearing the first of the four 
stronger tuberculate spiral ridges. The connections which join the tubercles 
in the spiral series are a little more strongly developed than those which 
link them vertically, the spaces inclosed between them being deep squarish 
pits. The tubercles are very prominent and rounded, there are about 
sixteen upon the second, twenty upon the third, and twenty-six upon the 
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