, found in
Mexico. The
species in this genus are characterized by their elongated fusiform spire and a long siphonal canal. The whorls show on their edge spinose projections. The shell is moderate in size, with a subacute, few whorled, glassy protoconch. It has an elongated slender, straight
siphonal canal. The
whorls are tabulated by a sharp recurved spinose or beaded keel, between which and the suture the surface is concave, nearly smooth. The
anal sulcus is deep, narrow, the fasciole separated from the suture by a beaded ridge, the outer margin of the fasciole not elevated. Type †
Pleurotoma cristata Conrad, 1848.
Oligocene fossil. This group is extremely close to
Ancistrosyrinx Dall, 1881, the latter differing only by having the anal sulcus at the suture, with no intervening ridge, while the outer margin of the fasciole has an elevated lamella between which and the reflected keel at the shoulder there is an excavated channel. These differences hold good between the Oligocene and the recent forms, so far known, without exception. The recent forms have an operculum like that of
Leucosyrinx. ==Distribution==