Original description of Rostellaria simplex by Gabb, 1864:
- "Shell elongated, robust; spire high; whorls about seven, rounded; suture distinct. Surface marked by numerous longitudinal ribs, small on the upper volutions, becoming larger, more distant, oblique, and proportionally shorter, as the shell increases in size; these are crossed by small, regular, revolving lines. Outer lip suddenly expanded; posterior canal continued along the surface of the penultimate whorl; anterior canal suddenly recurved. Aperture unknown."
Locus typicus: Eocene Téjon Formation of San Diego and Clayton, California, USA.
Rimella simplex Gabb, 1864, pl. XX; fig. 80
Cowlitzia simplex (Gabb, 1864); 31,95 mm; Coll. no. 112.01