DALL: MOLLUSCA AND BRACHIOPODA. 271 
Suture deep, appressed; whorls gently rounded; apieal whorls with (on the 
third whorl about fifteen) very narrow, sharp, threadlike, vertical ribs with much 
wider interspaces, and at the suture numerous, irregular, small, retractive folds 
extending over the fasciole, with wider interspaces, nearly twice as many as there 
are ribs; on the succeeding whorls these ribs and folds grow sparser and weaker, 
so that on the sixth whorl ribs, folds and fasciole are obsolete or absent; on the 
spire, the axial sculpture is crossed by (on the third whorl about eight, on the 
sixth ten or a dozen) fine flat threads with wider interspaces, (increasing by in- 
terpolation), which override the ribs and rise above them but do not form nodules 
at the intersections ; these spirals are very uniform and on the last whorl extend 
forward covering the canal, and are slightly scored by the incremental lines; aper- 
ture oval, not mature in the specimen, the anal sulcus obsolete; pillar and body 
polished, the surface erased, not callous; the pillar is short, gyrate, the axis per- 
vious, but the canal is short, rather wide, with no siphonal fasciole ; the outer lip 
only slightly produced, sharp and thin in the type specimen. Opereulum concen- 
tric, pointed in front, with an apical nucleus, Lon. of (decollate) shell, 23; of 
last whorl, 15; of aperture, 10.5; max. diam. 7 mm. 
U. S. S. “ Albatross,” station 2859, in the Pacific Ocean, in 1569 fathoms, 
ooze, bottom temperature 34?.9. U. 5. N. Mus. 122,590. 
This shell recalls Surculina, but has harsher sculpture and a large normal oper- 
culum. It may prove eventually to belong to a group other than Leucosyrinx. 
Irenosyrinx persimilis Datu. 
Plate 12, figure 2. 
Leucosyrine persimilis Dall. Proc. U. S. Nat. Mus., 1889, 12, p. 301, pl. 6, fig. 3. 
Shell large, white, fusiform, with a pale olive periostraeum, acute spire, and 
eight whorls, exclusive of the (lost) nucleus, each carrying a peripheral keel; 
suture distinct; whorls behind the periphery somewhat flattened, with a shallow 
constriction just behind the keel; axial sculpture only of incremental lines ; spiral 
sculpture between the suture and periphery of numerous flat, subequal, strap-like 
bands separated by narrower, shallow channels; periphery with a low, rather 
wide prominence, giving the effect of a keel and sculptured with several similar 
but larger, stronger and more distant bands, tending to arrange themselves in 
pairs, and with a fine, subsidiary spiral striation upon them; this sculpture ex- 
tends over the anterior half of the whorl, becoming finer and closer on the canal ; 
aperture elongate; outer lip thin, sharp; a wide, deep, anal sulcus on the posterior 
slope of the whorl about midway between the suture and the periphery ; anterior 
part of the lip arcuate, protractive; body with the sculpture erased, white, 
Polished; pillar short, twisted, in front obliquely truncate and gyrate, but not 
axially pervious; a touch of brown on the edge; canal wide, elongate, slightly 
recurved, with no fasciole. Lon. of shell, 95; of last whorl, 70; of aperture, 55; 
max. diam. of shell, 39; of canal, 7 mm. Opereulum brown, oval, the exterior im- 
brieately lamellose, the nucleus inside the apical end which is bluntly rounded. 
