Although a true _Fusconaia_, this species (or group of forms) stands isolated within the genus, in characters of the shell as well as in the soft parts. It differs from the species of the _subrotunda_-group (ind. _ebena_, _pilaris_ etc.) very markedly by its smaller size and by the very shallow beak cavities. The forms of the _undulata_-group (incl. _flava_, and the _cuneolus_- and _cor_forms) have generally also somewhat deeper beak cavities, and the shell has a more or less distinct posterior ridge, with a flattening or a shallow groove in front of it, characters which are missing in the _barnesiana_-group. As has been pointed out, in the latter group, the color of eggs and placentae is remarkable: in all other forms of _Fusconaia_, this varies from white to bright red. I introduce here another species, in order to show that the _barnesiana_-type is also represented outside of the Cumberland-Tennessee drainage, namely in the Ozarks. FUSCONAIA OZARKENSIS (Call) 1887. _F. ozarkensis_ Call, Pr. U. S. Mus. 10, ’87, p. 499, pl. 27. Tr. St. Louis Ac. 7, ’95, p. 33, pl. 18. _Lampsilis ozarkensis_ Meek & Clark, Bur. Fisher. Doc. no. 759, ’12, p. 18. _Pleurobema utterbacki_ Frierson, in: Utterback, Naiad. Missouri (Amer. Midland Natural 4, 1916, p. 86, pl. 5, pl. 20, f. 63). I have specimens from James River, Galena Stone Co., Mo., and White River, Cotter and Norfolk, Baxter Co., Ark., donated by L. S. Frierson and collected by A. A. Hinkley on July 30 and Aug. 2 and 5, ’14, A number of specimens (8) were preserved in alcohol, coll. July 30 and Aug 2, which all were gravid females, and one of each date had glochidia. This marks probably the end of the breeding season, and the species is tachytictic. There is some confusion with regard to this species. After the first description by Call, it has not again been recorded, except by Meek and Clark, and I believe, the identification of these authors (supported by B. Walker) is correct. But I think that other authors have seen this form, but have not recognized it, and, for instance, Simpson’s _pannosus_ and _subellipticus_ (regarded as varieties of _Pleurobema argenteum_ and _breve_ respectively) are also this. Frierson’s _utterbacki_ is surely this, since my specimens were thus labeled by Frierson.