A new species of Eastern Pacific Fissidentalium (Mollusca: Scaphopoda)

Fissidentalium erosum sp. nov. is described morphometrically From specimens collected from deep water off California. II is distinguished from F. megathyris primarily on the basis of soft-body-part proportions and radular characteristics. Shell differences are slight; the ventral aperture of F. erosum is approximately circular, whereas in F. megathyris the aperture is distinctly wider than high. The posterior portion of Fissidentalium erosum shells is often eroded, in contrast to the uneroded condition of most F. megathyris shells collected at the same station.