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Description
Lamarck described the brook floater in 1819 from the Schuylkill River in Pennsylvania. This species has a fairly small, thin, rhomboidal shaped shell that rarely exceeds 70 mm in length, 40 mm in height, and 30 mm in width. The conspicuous posterior slope is broad and flat to slightly concave, with numerous short, low corrugations radiating toward the posterior margin at right angles to the growth lines. The periostracum is yellowish or brownish with numerous dark green or black rays. The nacre is glossy, bluish white and grades into a pale orange in the umbo area. The hinge teeth are poorly developed. Each valve has one small thin, triangular pseudocardinal tooth and lateral teeth are lacking or vestigial. This species has a bright orange foot.

Distribution (see map)
The brook floater is found in Atlantic Slope river basins from the Savannah River Basin in South Carolina north to the St Lawrence River Basin in Canada. It has also been found in the Greenbrier River (Ohio River Basin) of West Virginia. It is considered more common in the northern part of its range. Distribution by County: Catawba River Basin: Burke Co. (Linville River, Warrior Fork, and Johns River subbasins); Pee Dee River Basin: Surry Co. (Mitchell River Subbasin), Randolph Co. (Caraway Cr. and Little River subbasins), Montgomery Co. (Little River and Barnes Cr. Subbasins); Cape Fear River Basin: Moore Co. (Deep River), Chatham Co. (Rocky River Subbasin); Neuse River Basin: Orange Co. (Eno River Subbasin) NOTE: All headwater areas that flow into these occupied habitats should receive special management.

Habitat Preferences
This species inhabits medium size streams and rivers. It prefers clean, swift waters with stable gravel, or sand and gravel substrates. However, individuals found near the mouth of the Linville River in North Carolina were observed in sandy/silty substrate in cracks between boulders along a steep bank, in 1 to 3 feet of water and relatively slow current.

Life History
The brook floater is a bradytictic breeder. Gravid females have been found from August through May. Identified fish hosts include blacknose dace, golden shiner, longnose dace, margined madtom, pumpkinseed, slimy sculpin and yellow perch (Shultz and Marbain 1998)