Original Combination:

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Original Description:

At first glance this species would be readily taken for P. stenotrema and as it may exist in some collections under that name it can best be described by comparison with that well-known and widely distributed species.
Viewed from above, the difference is at once apparent, as barbata has stiff hairs about ½ mm. in length which are widely spaced, and the diagonal series cross the lines of growth at nearly a right angle. The upper half of the outer lip is well reflected, not appressed as in stenotrema and there is a distinct constriction back of it. From below the difference is still more striking, as the width of the mouth in barbata is fully double that of stenotrema ; in barbata the width, measured from the top of the tooth to the edge of the lip just below the notch, is 1 mm., while in a stenotrema of the same size it is only about 1/2 mm. The lamelliform tooth is more sinuous and less massive. The flattened upper lip, which is markedly concave, has a well pronounced tooth just opposite the upper end of the abruptly truncated parietal tooth. The " fulcrum," which is plainly visible through the shell, is the most pronounced feature, as it is 3 mm. in length, extending from the axis fully half way across the body-whorl. Embryonic, whorls polished and obsoletely ribbed, while in stenotrema they are granulated. The granulated embryonic whorls of Stenotrema and its allies, would seem to make the section Stenotrema of at least subgeneric value, although the almost smooth apex of barbata indicates that there is some variation in the group. The young of barbata are umbilicate. In size there is a wide variation in this species but in all other particulars the characters are absolutely constant.
Greater diam. 11, lesser 10, altitude 7 mm.
Greater diam. 10, lesser 9, altitude 6 1/2 mm.
Greater diam. 8, lesser 7 1/2, altitude 5 1/2 mm.
The average diameter is 9 to 10 mm. Whorls about 5 1/2.
Types from the flood-plain of the Tallapoosa River near the Montgomery Road about five miles southeast, of Wetumpka, Ala., in collections of Geo. H. Clapp and Acad. Nat. Sci. Phila. This most interesting species was first found by Mr. Herbert H. Smith in November, 1903, and he reports it scarce and apparently very local.
On Poole's Island in the Coosa River just below the Georgia line, in Alabama, Mr. Smith found a smaller form of barbata which differs slightly in the mouth being still wider and the lip notch weaker. It averages from 8 to 9 mm. diam.