Shell in many respects resembling S. lignarius and best described by comparison with it; shell of a livid or grayish straw color, not the yellow or reddish brown of lignarius; the tip of the spire is smaller in proportion and more pointed; the axis is pervious as in lignarius, but the perforation is more cylindrical and does not become funnel-shaped as the shell enlarges to maturity; the shell averages more slender; the callus on the body is not reflected so far and especially on the anterior part of the pillar; the grooves of the surface in S. lignarius, without exception, are continuous, the punctures being arranged along their channels; in S. interruptus the spiral sculpture is composed of rows of short or longer punctuations or grooves, which do not unite to form a continuous line except close to the columella in front, and here rather as the result of crowding and overlapping; these short grooves are not punctate at bottom as in S. lignarius, but are apt to alternate stronger and weaker, and are more closeset than in lignarius of the same size; maximum longitude of shell,33; maximum latitude of shell 17.5; of aperture, 13.5MM.

West coast of Patagonia, in 1,050 fathoms, mud, temperature 37°; and near the Galapagos Islands