Finelined Pocketbook

The finelined pocketbook is suboval in shape and can grow to 117 mm in length (Williams et al. 2008). It is yellow-brown to blackish and occurs in small creeks to large rivers. It has been found in sand, gravel, and gravel-cobble substrates without heavy silt deposits (Williams et al. 2008). The ventral margin of the shell is angled posteriorly in females, resulting in a pointed posterior margin. The periostracum is yellow-brown to blackish and has fine rays on the posterior half. The nacre is white, becoming iridescent posteriorly. The finelined pocketbook can be distinguished from a similar species, the orangenacre mucket, by its more elongate shape, thinner shell, white nacre, pointed posterior, and ray ornamentation (68 FR 14752).