Description. Shell small, about 7 mm. in length, high, the height being about two thirds of the length. Base broadly ovate. Anterior slope convex, posterior slope concave. Apical whorls one and one half, prominent, placed high on the shell and just in front of the posterior end. Anal fasciole and fissure with I he borders ridged. The fasciole with widely-spaced incremental lamellae. The fissure is rounded behind and tapers to a sharp point in front. Sculpture consists of about 25 radiating, very strong, ribs between each two of which there is a finer one. The shell is crossed by concentric threads which form elongated nodules where they intersect the ribs. Color white. Margin finely crenulated. In the interior of the shell the anal fasciole is rather heavily thickened.
Remarks. This species, while quite different from any other in the Western Atlantic, appears to be nearer R. aeguiscuipta than to the rest of the species. It differs from aequisculpta in being higher, heavier, with coarser sculpture. In addition, its apex is much larger and more prominent, the anal fasciole is more conspicuous and its growth increase is shown by lamellae rather than by threads, such as occur in R. aequisculpta.