286 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
except for lines of growth, bordered in front by an inconspicuous angular 
shoulder ; from this shoulder extend (on the last whorl about eighteen) feeble, nar- 
row, subequal, protractive, axial riblets, with subequal interspaces, crossed by fine, 
close-set spiral threads ; the ribs extend to the suture, or on the last whorl to the 
base, and the threads cover the whole surface; anal sulcus shallow, outer lip 
thin, simple, moderately arcuate; pillar and body smooth, the former obliquely 
attenuated in front, not pervious; canal short, wide, slightly recurved; Lon. of 
shell, 4.9; of aperture, 2.6; of last whorl, 3.7; max. diam. 2.0 mm. 
U.S. 8. “Albatross,” station 3418, off Acapulco, in 660 fathoms, sand, bottom . 
temperature 39°F. U.S. N. Mus. 123,118. 
Mangilia cetolaca Datt, n. sp. 
Aesopus oldroydi Arnold, Mem. Cal. Acad. Sci., 1903, 3, p. 238, pl. 6, fig. 7. Not 
Mangilia oldroydi Arnold, op. cit. p. 213. 
Lower Pleistocene of San Pedro, California, Arnold. 
Living at U. 8. 8. ‘* Albatross,”’ station 2835, at Ballenas Lagoon, Lower 
California (N. Lat. 26° 42’ 30” ), in five and a half fathoms, temperature 56°F. 
Mangilia enora Da tt, n. sp. 
Plate 4, figure 6. 
Shell small, yellowish-white, decollate with about six whorls beside the (lost) 
nucleus, the spire longer than the aperture; suture distinct, not appressed, with 
a broad anal fasciole in front of it, arcuately sculptured by lunate wrinkles follow- 
ing the lines of growth and in the earlier whorls elevated into sharp wrinkles at 
regular intervals, which are carried more or less distinctly over the anterior part 
of the whorls; in front of the somewhat concave fasciole the whorls are rounded 
and spirally sculptured with numerous close, very fine, sharp, spiral threads which 
cover the whorl, becoming coarser, less regular, and less crowded toward the 
canal; aperture short, lunate; outer lip with a broad, deep, rounded, anal sulcus 
close to the suture, the lip in front of it thin, sharp, and strongly arcuately pro- 
tractive; body smooth; pillar very short, smooth, obliquely truncate; the canal 
very short, deep, recurved, forming a marked siphonal fasciole; operculum ab- 
sent. Lon. of shell, 9.5; of last whorl, 5.7; of aperture, 4.0; max. diam. 
4.2 mm. 
U.S. S. “ Albatross,” station 3376, off the coast of Ecuador, in 1132 fathoms, 
ooze, bottom temperature 36°.4 F. U.S. N. Mus. 123,121. 
Mangilia? genilda Da tt, n. sp. 
Plate 13, figure 3. 
Shell small, white, with about six whorls exclusive of the (lost) nucleus ; suture 
distinct, the whorl in front of it slightly turgid, in front of which the anal fasciole 
