The triangular kidneyshell is oval to elliptical in outline, and can reach 85 mm in length (Williams et al. 2008). The shell is moderately compressed, and may be flattened ventral to the umbos. The posterior ridge is high, rounded and the posterior slope is moderately steep. The pseudocardinal teeth are heavy, and the laterals are heavy, straight to slightely curved and short. The periostracum is tawny to brown, usually without rays, but when present are thin, sparse, and usually confined to the posterior slope (Williams et al. 2008).