The functional morphology of the genus Estellacar is described and the unusual elliptical form is shown to be an infaunal character. Although the length:height ratio is typical of epibyssate arcoids Estellacar displays numerous infaunal traits especially the labial palps which are the largest yet observed in the Arcoida. Estellacar is shown to be a valid genus and having close similarities to the Eocene genus Rectangularca. The probable phylogeny suggests that any association with Striarca or the Striarcinae is artificial. The species are described, and include E. saga, E. olivacea, E. galactodes and R. africana. The systematics of ‘Barbatia’ pectunculiformis (Dunker) are reviewed. Although this species is most like Estellacar the differences in shell form are considered to be significant enough to warrant separate generic status, as Scelidionarca n. gen.