Original Combination:

Troosti = comfort [latin]

Original Description:

Testa superne subplanulata, inferne subinflata, cornea, longitudinaliter striata, late umbilicata; anfractibus senis; apertura lunata, tridentata.
Shell above nearly flat, below somewhat inflated, horn-coloured, longitudinally striate, widely umbilicate; whorls six; aperture lunate, three-toothed.
Hab. Tennessee. Professor Troost.
My Cabinet. Cabinet of Professor Troost
Diam. .4, Length .2 of an inch
Remarks. — This species strongly resembles P. Dorfeuilliana. here-in described, being nearly of the same size, and possessing most of its characters. It differs, however, in the large solid tooth on the left lip being more angular, and in the two teeth on the right lip being somewhat differently placed. In the striae it differs much, these being larger, much better defined, and passing entirely over the whorls. In the umbilicus it is wider, and shows more of the two whorls. This shell forms the fourth of a group, the form of the apertures of which is exceedingly alike, viz. P. fatigiata (Say), P. plicata (Say), and P. Dorfeuilliana (nobis).