Shell compressed, inequilateral, equivalve. Posterior end rostrate, submedial or medial, pointed. Periostracum varnished, adherent. Sculpture absent, or commarginal, rarely with superimposed oblique lirae. Hinge plate with two series of small taxodont teeth, separated by narrow resilifer. Ligament amphidetic, with small internal resilium. Intestine long, coiled.
The name is a diminutive derived from the Greek bathys, deep, and the Latin spina, a thorn, and is feminine. Two subgenera are known, both represented in the northeastern Pacific.

Bathyspinula, s.s.
Shell thin, compressed. Rostrum subdorsal, wide, with bluntly pointed tip. Sculpture of commarginal striae and several oblique striae intersecting commarginal sculpture on ventral surface.