Leucosyrinx tenoceras: Shell long, very slender, the aperture longer than the spire behind it; white or ashy, the nucleus yellowish, subglobular, glassy, smooth ; whorls ten, beside the nucleus ; suture appressed, a coronet of short, elevated, backward pointing wrinkles marginating the whorl in front of it; fasciole wide, with obsolete sculpture or smooth, polished, very sloping, subconcave ; shoulder of the whorl angulated, ornamented (on the whorl before the last) with about fourteen nodular riblets ; these riblets on the early whorls are short, stout, and very prominent, later they become more slender and oblique, and on the last whorl tend to become obsolete entirely ; the whole shell except the fasciole is covered with fine flattened threads, not prominent, and often wavy or obliquely directed from irregularities of growth ; aperture long, rather narrow; canal narrow, long, flaring a little at the end ; outer lip thin, simple, broadly arched forward, with no internal lirae; notch deep, very wide, extending from the suture to the shoulder ; pillar lip slightly excavated, white, smooth; pillar straight, attenuated in front ; whorls moderately full, having a drawn-out appearance; operculum thin, pear-shaped, acutely pointed, with a thin marginal rib ; pale horn-color. Long. of shell, 60.0 mm ; of last whorl, 40.0 mm; of aperture, 33.0 mm; max. lat. of shell, 14,0 mm.

Leucosyrinx sigsbei: Shell in general closely resembling Leucosyrinx verrillii, with the following differences : it has the same number of whorls in 25.5 mm. length ; it is proportionally more slender ; the knobs are oblique instead of perpendicular, in the spire are set in the middle of the whorls instead of near the suture, are less prominent, and become obsolete toward the end of the last whorl; there are about eighteen on the last whorl that has them, and they are proportionally more produced than in the last; the pillar is less twisted and the sharp flaring edge near the anterior end is not so prominent; the nucleus is smooth and light brown : the remainder of the shell has a brownish tinge compared with the preceding. Long. 25.5 mm; of last whorl, 15.0 mm; of aperture, 11.75 mm, Max. lat. 9.3 mm.

Leucosyrinx tenoceras: Gulf of Mexico and Caribic. In the north to the coast of North Carolina.

Leucosyrinx sigsbei: Gulf of Mexico. Yucatan Strait.