388 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
the ribs extend well down over the body whorl, where they fade out; the rather long base is strongly, 
spirally lirate; varix high; columella nearly straight. Color of the shell white, pink, or purplish. 
Length of largest specimen, 8; diameter, 3 mm. 
Mayaguez, Porto Rico. 
Genus BORSONIA Bellardi. 
Subgenus Cokdieria Rouault. 
? Borsonia rouaulti Dali. 
Borsonia ( Cordieria ) rouaulti Dali, Blake Report, n, p. 98, pi. xxxvi, fig. 11, 1889. 
Three young, worn specimens, which were obtained at. Mayaguez, may be referable to this species, 
but they are not in condition to be identified with certainty. 
Genus MANGILIA (Leach) Risso, 1826. 
Shell fusiform, imperforate, terminated below in a rather short canal; aperture oval-elongate; lip 
more or less notched above; no operculum. 
Subgenus Cytfiara Schumacher, 1817. 
Shell longitudinally costate; external surface usually finely gran ulostri ate; outer lip denticulated 
within; inner lip striate; aperture narrow, elongate. 
Mangilia asarca, n. sp. Plate 57, fig. 14. 
Shell minute, white, or with faint yellowish flammules, with six brilliantly polished, slender 
whorls; nepionic shell small, depressed, smooth, subsequent whorls with about ten axial riblets, 
slightly flexuous near the suture and becoming obsolete anteriorly, the peripheral part of the last whorl 
smooth or destitute of spiral sculpture, which on the base and canal is well developed and consists of 
fine striation; notch short, subcircular, leaving no fasciole; outer lip slightly thickened, not lirate within. 
Length, 4.5; maximum diameter, 1.5 mm. 
Mayaguez, Porto Rico. 
This is a small but elegant species, which differs from the majority of its congeners in the absence 
of the fine, frosty granulation of the surface which is so characteristic of many of them, and in the 
somewhat obscure development of the axial ribs. 
Mang-ilia balteata Reeve. 
Mangilia balleala Reeve, Conch. Icon.) in, pi. vii, fig. 57, 1846. 
Spire elevated, whorls but slightly rounded, having about six strong, straight, longitudinal ribs, 
which are nearly continuous and are only partly interrupted by the suture; surface generally sculp- 
tured with faint, revolving threads; aperture two-fifths of the length of the shell; canal not lengthened. 
Color generally whitish, encircled with a median chestnut zone, which is sometimes wanting. 
Length, 12; diameter, 4 mm. 
Three fragments were obtained in Mayaguez Harbor. 
Mangilia densestriata C. B. Adams. 
Many ilia densestriata C. B. Adams, Contr. to Conch.. 1850, p. 65. 
Shell fusiform, with seven whorls, which are shouldered above, and have from eight to twelve 
strong, nearly straight ribs, the last whorl having but eight ribs; suture deep; surface everywhere 
covered with fine but sharp, high, revolving threads, which are not interrupted on the ribs; notch in 
the outer lip shallow; base slightly attenuated; canal wide. Color white; in one specimen there are 
three faint, broken, revolving bands on the body whorl, which show most distinctly on the ribs; in 
another there are only a few scarcely perceptible dots on the ribs in two rows. 
Length, 6; diameter, 2.25 mm. 
Mayaguez Harbor, Porto Rico, one nerfect and one broken shell. This agrees very well with the 
description by C. B. Adams of his Mangilia densiclathmta. His specimen or specimens were white. 
