Distribution. Known from a few stations off New England at abyssal depths.
Remarks. The material shows some variation in the strength of the axial threads between the strong axial ribs; under close examination some specimens show a finely granular surface. This character is obsolete in other shells. Some shells are also broader and have a stronger subsutural spiral line.
P. sandersoni has a rather big larval shell (diam. c. 800 µm), rather regularly conical profile and a sculpture of axial ribs which start very abruptly, just below the subsutural zone and then decrease in height. The spiral sculpture consists of equal-sized spiral ribs which make small nodules at their intersections with the axial ribs. The surface of the shell is rather distinctly granular. P. benedicti has a rather big (diam. c. 800 µm) and broad larval shell. The sculpture consists of strong axial ribs, highest at the middle of the whorls and a few stronger and several smaller spiral cords which form small nodules at the intersections with the axial ribs. The shape is rather slender and the whorls distinctly convex.