As Priotrochus alexandri

This fine species is evidently allied to obscurus Wood, but differs in several particulars: It is more depressed and broader, the maximum diameter exceeding the altitude, whereas in obscurus the reverse is the case, and the umbilicus is larger and more open; the peripheral keel is sharply acute, widely and equally separated above and below from the next spiral ridge ; in the type the ridge above is fine but well marked, but in another example this ridge is absent; there is a regular row of tubercles at the shouldering of the whorl; below the periphery are seven sharply raised ridges, the interstices being distinctly concave.
Altitude 16,5 mm., max. diam. 18 mm.
HAB.—Algoa Bay (C. W. Alexander).