Lirobittium Bartsch, 1911. Type species (OD): Bittium (Lirobittium) catalinensis Bartsch, 1911; = Bittium purpureum Carpenter, 1864. Northeastern Pacific.

Diagnosis. Shell small, tall, whorls moderately inflated; sculpture axial and spiral, usually reticulate; sculpture of base spiral; anterior canal very shallow, anal sinus weak, lip thin, smooth. Protoconch of two and one-half whorls, becoming bicarinate early to late on second protoconch whorl.
Biology. Direct development has been noted for the intertidal species Stylidium eschrichtii (Middendorff, 1849) by Strathmann (1987:241). Reproduction in other northeastern Pacific species has not been studied, and there are no papers that treat the biology of any species in the group.
Remarks. Northeastern Pacific species are unlike those of typical Bittium of the northeastern Atlantic and Mediterranean in having sculpture of spiral carinations on the second and third whorls of the protoconch. Anatomical differences were found by Houbrick (1993), who assigned the species other than Stylidium eschrichtii to the genus Lirobittium Bartsch, 1911.
Eastern Pacific species were last reviewed by Bartsch (1911), who proposed an excessive number of names, of which many are now relegated to synonymy. The numerous synonyms are an indication of the high variability among the species. Shallow-water species were reviewed by McLean (1978). The synonymies given here are based on my study of type material of all eastern Pacific members of the group.