276 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
cords render their junction with the axial ribs strongly nodulose. The 
nodules of the cord at the summit are rounded; those of the other two cords 
are truncated posteriorly and slope gently anteriorly. The pits inclosed be¬ 
tween the axial ribs and spiral cords are almost rounded. Periphery marked 
by a strong spiral cord which is separated from the first supraperipheral 
cord by a groove about as wide as that separating that cord from the 
median of the spire. The groove is crossed by the continuations of the 
axial ribs which extend feebly over the cord and render it weakly tubercu- 
late. Base short, well-rounded, marked by four strong spiral cords which 
grow successively weaker from the posterior anteriorly. These are sepa¬ 
rated by grooves much narrower than the width of the cords, and they are 
rendered slightly tuberculated by the slender continuation of the axial 
ribs. Aperture subquadrate, decidedly channeled anteriorly; posterior angle 
obtuse; outer lip thin, showing the external sculpture within, rendered 
sinuous at the edge by the external sculpture; inner lip sigmoid. 
Type in United States National Museum, No. 340935. Type locality, 
Monterey Bay. It has nine whorls and measures, length, 7.4 mm.; diameter, 
2.9 mm. 
Cerithiopsis santacruzana Bartsch, 1927 
Proceedings of the United States National Museum, 70:27; PI. 5, fig. 2. 
Shell stout, very broadly conic, pale brown. Early nuclear whorls decol¬ 
lated, the last one and one-half marked by very slender, distantly spaced, 
decidedly protractively slanting axial riblets, while the broad spaces be¬ 
tween them are marked by slender raised threads which are placed at right 
angles to the axial riblets. Postnuclear whorls moderately rounded, marked 
by strong, retractively slanting axial ribs. Of these, 16 occur upon the first 
to fourth, 18 upon the fifth, 20 upon the sixth and seventh, and 22 upon 
the penultimate turn. The spaces which separate the axial ribs are about 
as wide as the ribs. In addition to the axial sculpture, the whorls are 
marked between summit and suture by three strong spiral cords, of which 
the first, which is at the summit, is a little weaker than the other two on 
all the turns but the last. The junction of the axial ribs and spiral cords 
form strong tubercles which are truncated posteriorly and slope more 
gently anteriorly. The spaces inclosed between them are roundish pits. 
Suture moderately impressed. Periphery of the last whorl marked by a 
rather strong cord. The space separating this from the cords of the spire 
is crossed by the continuation of the axial ribs, which extend to the cord 
but do not cross it, nor do they tuberculate it. Base short, moderately 
rounded, marked by a spiral cord which is a little less strong than the one 
at the periphery from which it is separated by a channel a little narrower 
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