Shell elongated, acute, many-whorled, dextral, with a small, sinistral nucleus, spirally or reticulately sculptured; aperture ovate, lips thickened; columella straight, simple, without plaits, a basal cord entering the aperture on the body between the pillar and the outer lip; aperture anteriorly a little effuse, but not channeled in front of the pillar; outer lip varicoid in the adult, internally with a few very strong line.
Type, Peristichia toreta Dall.
This genus has the spire, sculpture, and nucleus of Mathilda, the basal cord is like that of Oscilla nivea; the outer lip, though less patulous and more varicose, has something about it which recalls Rissoina, It is like an Oscilla without columellar plaits, or like a Mathilda with a thickened and internally lirate peritreme and rounded base. As far as one may judge from the characters of the shell alone, this genus would indicate the passage between Mathilda and Oscilla.