Original description.
Shell small, acicular, with the keel at the summit and the base light brown, the rest white. Nuclear whorls five, ornamented with two ratlier closely placed spiral threads, the posterior one of which marks the middle of the exposed portions of the nuclear whorls, and many slender, axial riblets, of which there are about twenty-four upon the fourth and twenty-eight upon the fifth turn. Post-nuclear whorls eight, separated by deep channeled sutures, ornamented on the early whorls by two strongly tuberculated keels, separated by a deep channel, which is crossed by the moderately strong axial riblets, which connect the tubercles of the two ridges. Beginning with the fourth whorl a slender keel makes its appearance between the other two, which rapidly increases in size, becomes tuberculated, and on the penultimate and last turn exceeds the basal keel in strength. There are about fourteen riblets U])on the first, twenty upon the fifth, and twenty-two upon the penultimate, post-nuclear whorl. Base marked by three non-tul:)erculated, equally strong and equally spaced sj^iral ridges. Aperture irregular, pyriform, strongly channeled posteriorly and anteriorly, with a rounded opening at the anterior extremity of the short, stout, twisted columella. Parietal wall and columella covered by a strong callus.
Original description of Triphoris galapagensis var. postalbus Bartsch, 1907 and Triphoris galapagensis var. unicolor Bartsch, 1907.
Two striking color forms of this species were found in the lot obtained from the above station. One, represented by a single specimen, Cat. No. 105380, U.S.N.M., which may be known as variety postalhus, fig. 5, has the posterior and median keel white, the rest brown. The other variety, unicolor, fig. 13, represented by nine specimens, Cat. No. 105379, U.S.N.M., is uniformly brown.