Shell small, turbinate, umbilicate; lip with either slit or foramen; operculum multispiral. Shell structure of lamellar aragonite, interior lacking nacre. Ctenidia paired, the left larger than the right, ctenidial filaments finger-shaped. Left kidney a papillary sac; columellar muscles paired. Cephalic lappets and neck lobes lacking, cephalic tentacles setose, epipodial tentacles setose (except first 2 pairs); mantle margin with small papillae and setose pallial tentacles projecting through slit. Rachidian tooth of radula broad at base, tip narrow, with finely denticulate, overhanging cutting edge; first 4 lateral teeth cusped like rachidian and with broad basal areas overlaping adjacent laterals; fifth lateral larger and having long, finely denticulate tip; marginal teeth numerous, with long, serrate tips.
Biology. Scissurellids occur on soft bottoms offshore and on rock and gravel bottoms in shallow water. What little is known of the biology of scissurellids is based on knowledge of Anatoma crispata, as detailed by Fretter and Graham (1962,1976). That species feeds on detrital material; its reproductive biology is unknown.
The most recent account of scissurellid anatomy is that of Haszprunar (1989).
Remarks. The Scissurellidae have small white shells with an open slit or foramen, which serves as an excurrent opening for water currents passing through the mantle cavity. Scissurellids resemble the much larger pleurotomariid slit-shells. Most scissurellid species occur offshore, where they are often overlooked because of their small size.
The Scissurellidae have long been recognized as a family. Based on anatomical differences from the Pleurotomariidae, the group has recently been elevated to the superfamily level (Haszprunar, 1989; McLean, 1989), an action more recently supported by studies of pleurotomariid sperm morphology by Healy and Harasewych(1992).
McLean (1989) offered a subfamilial classification of Scissurellidae based on gill and protoconch characters, recognizing four subfamilies. In addition to the typical subfamily, three were proposed as new: Anatominae, Temnocinclinae, and Sutilizoninae, the last two restricted to the hydrothermal-vent habitat.