Salter's original specimen comes from the Wenlock Shale, Builth Bridge, and was described (Salter, loc. cit.) as having “much narrower whorls than Phr. nautileum.” The specimen consists only of the greater portion of the outer whorl, including the body-chamber, and it shows the aperture and ornamentation very well preserved. It agrees with Blake's species Tr. striatum in shape, rate of increase, characters of body-chamber and aperture, degree of obliquity of the transverse ribs, their absence on the body-chamber, the fine lines parallel to them on the rest of the whorl, the epidermids, and the shape, position, and distance apart of the septa. The stratigraphical horizon on which it is found is also the same, and there can be no doubt that the species are identical, as they agree in all the essential characters and even in every minute detail.