CLASS GASTROPODA 
275 
Cerithiopsis stephensae Bartsch, 1909 
Plate 69, fig. 7 
Proceedings of the United States National Museum, 37:399. Also 40: PI. 39, fig. 7. 
Shell elongate-conic, chocolate brown. (Nuclear whorls decollated in 
all the specimens seen.) Post-nuclear whorls well-rounded, ornamented 
spirally by four keels between the sutures, of which the posterior three are 
strong and tuberculate, the fourth smooth and slender. Axially the whorls 
are marked by irregular ribs, the junctions of which with the spiral keels 
form tubercles. The posterior row of tubercles is at the summit and is the 
weakest, the individuals appearing as rounded knobs. The second is on the 
middle of the whorl. This and the first, which is immediately above the 
peripheral sulcus, have their tubercles of about equal strength. On these 
two keels the tubercles slope gently anteriorly and very abruptly posteriorly. 
The peripheral sulcus and the other two sulci are equally strong and wide. 
All are crossed by ribs, which, however, do not extend over the base. 
Both spiral cords and ribs are crossed by strong incremental lines. Sutures 
constricted. Periphery of the last whorl marked by a deep channel. Base 
well-rounded, rather short, marked by strong incremental lines and a few 
very fine spiral striations. The summit of the succeeding whorl drops a 
little below the peripheral sulcus in all the whorls of the spire and allows 
a narrow margin of the smooth base to appear as a cord in the suture. 
Aperture ovate, with a strong anterior sinus, outer lip thin, showing the 
external sculpture within; columella stout, twisted and curved, having 
a weak basal fasciole at its insertion. Length, 9; diameter, 2.1 mm. 
(Bartsch.) 
Type in United States National Museum, No. 204008. Type locality, 
Bear Bay, Peril Strait, Alaska. 
Range. Fort Frederick, Alaska, to Puget Sound. 
Cerithiopsis fia Bartsch, 1927 
Proceedings of the United States National Museum , 70:26; PI. 5, figs. 6, 7. 
Shell broadly conic, chestnut-brown. Nuclear whorls decollated except¬ 
ing a portion of the last turn which has numerous slender distantly spaced, 
retractively slanting axial threads and numerous fine spiral threads in the 
intercostal spaces which are placed at right angles to the axial ribs. Post- 
nuclear whorls moderately rounded, marked by almost vertical axial ribs 
of which 14 occur upon the first and second, 16 upon the third and fourth, 
18 upon the fifth and sixth, 20 upon the seventh, and 22 upon the last turn. 
These ribs are about as wide as the spaces that separate them. In addition 
to the axial sculpture, the whorls are marked by three strong spiral cords 
of which the first at the summit is a little weaker than the rest. These 
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