274 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
lines of growth, crossed by numerous very sharp, narrow, prominent, subequal 
spiral ridges with about equal or narrower interspaces ; the periphery is formed by 
a sort of rib, on which stand two to four similar keels, but smaller than the others 
and more crowded; in front of the rib there is a faint constriction of the whorl ; 
the keels are less prominent on the canal, which is moderately long and recurved; on 
the penultimate whorl there are about fourtcen keels between the sutures; aperture 
elongate, reflecting the sculpture, but without lirae; outer lip very flexuous, with 
a broad, rather shallow anal sulcus behind, and arched forward in front of the 
peripheral rib; body white, not callous; pillar thin, attenuated, and obliquely 
truncate in front, concave, twisted, exhibiting a pervious axis; canal shallow, not 
producing a fasciole; operculum like that of Mohnia frielet. Height of shell, 60; 
of last whorl, 48; of aperture, 28; max. diam. 26 mm. 
U. 8. S. “ Albatross,” station 3415, off Acapulco, Mexico, in 1879 fathoms, 
globigerina ooze, bottom temperature 36°F. U.S. N. Mus. 123,099. Also at 
station 3381, east of Malpelo Island, Gulf of Panama, in 1772 fathoms, mud, 
bottom temperature 35°.8 F. U.S. N. Mus. 123,098. 
The initiatory part of the operculum is spiral, as in Mohnia, thus differing from 
the typical deep-water Turritidae, which it in general resembles. They have the 
nucleus of the operculum apical and not spiral. It differs from the operculum of 
Trenosyrinx in being enlarged at the inner posterior margin as in Lunatia, so that 
the spiral apex remains apical, while in Irenosyrinx the operculum after a brief 
period of spiral growth is entirely surrounded by concentric additions, so that the 
spiral portion is within a subsequent concentric margin, like the nucleus of the 
operculum in Buccinum. 
CALLIOTECTUM Datt. 
Calliotectum Dall, Proc. U. S. Nat. Mus., 1889, 12, p. 304. 
Calliotectum vernicosum Datu. 
Calliotectum vernicosum Dall op. cit., p. 304, pl. 5, fig. 8, 1889. 
U.S. 5. ‘‘ Albatross,” station 2798, off the coast of Ecuador, in 741 fathoms, mud ; 
station 2807, near the Galapagos Islands, in 812 fathoms, mud, bottom tempera- 
ture in both cases 38°.4 F. Also at station 3407, off the Galapagos Islands in 
885 fathoms, bottom temperature 37°.2; and at station 4654 twenty-four miles 
W. 68° N. from Aguja Point on the Peruvian coast, in 1036 fathoms, mud, bottom 
temperature 37°.3. Both the latter stations afforded fragmenis:orily. 
A full account of the animal was given in the publication of 1389. 
