Elliptio marshii (Wright, 1888) 

1. Lake Monroe, Volusia Co., FL - 70 mm
2. Lake Rosalie, Polk Co., FL - 38 mm
3, 4. Lake Sampson, Bradford Co., FL - 3: 53 mm; 4: 50 mm

Type locality: Blue Springs [St Johns River system], Florida.

Range: St Johns and upper Kissimmee River systems.

Remarks: This is a nagging species that, on the one hand, seems an extreme variant of buckleyi, but on the other hand, may be found sympatric with it. It is an elongate form having a peculiar gray-green color, usually rayless, with the umbo far forward, a concave dorsal ridge, and a bowed ventral margin. The nacre is rarely as purple as in buckleyi. It seems to be a lake species.

Unio tryoni Wright, 1888, is a synonym; marshii has page precedence.