Shell smaller, narrower and less robust than T. bilabiata. The costae are more bladelike and show a considerable variation in their spacing; they are of equal height and show no tendency to become smooth at the whorl periphery. The lip is bilabiate and the aperture is holostomatous, the inner lip not being attached to the parietal area. Length 4,5 mm; Width 1,8 mm

This species appears to be quite well marked. It differs from T. bilabiata by being smaller and narrower and is in general a far more delicate shell. As stated in the description, the costae are more blade-like, quite different from the more rounded and lower costae of bilabiata. All specimens so far seen have the costae strongly developed and of equal height throughout their length. In bilabiata there are many specimens that have the peripheral area smooth and others are almost entirely smooth. The whorls in bahamensis are nearly of equal size so that the sides of the shell are almost parallel. In bilabiata successive whorls are slightly larger, resulting in a more tapering spire.