280 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
shoulder, behind which it is slightly excavated; this area is spirally sculptured 
with numerous, very fine, close-set threads, one of which, two-thirds of the way 
to the keel, is more prominent than the others; these are crossed by numerous 
rather irregular low sharp ridges strongest near the keel, which they nodulate 
more or less, especially on the earlier whorls, and, fading out toward the suture, 
faintly retieulating the spirals; keel high, sharply compressed below, with a rounded 
edge; whorl in front of it spirally sculptured with numerous flat low ridges with 
narrower channelled interspaces, the ridges crossed by fine sharp lines of growth 
and occasional faint vertical folds, low and obsolete except near their beginning in 
front of the keel; body polished, with the sculpture erased ; outer lip angulated 
and notched by the keel, thin, sharp, simple; pillar short, white, with a faint brown 
band around it; the anterior portion acute, and obliquely truncate; canal short, 
slightly recurved. Lon. of (eroded) shell, 12.5; of last whorl, 11.0; of aperture, 
9.0; max. diam., 7.7 mm. 
U. 8. S. “ Albatross,” station 3393, Gulf of Panama, in 1020 fathoms, mud, 
bottom temperature, 369.8 F. U. S. N. Mus. 123,112. 
This is quite a peculiar shell, and looks more like one of the northern Belas 
than any of the preceding species. 
Pleurotomella (Gymnobela) xylona Darr, n. ep. 
Plate 2, figure 3. 
Shell thin, white, elongate, subturrited, with eight whorls beside the (lost) 
nucleus; suture distinct, deep, not channelled; whorl in front of it sloping flatly 
to an angular shoulder, sculptured with three or four flattish spiral threads with 
slightly wider interspaces separated from the keel at the shoulder by a channel 
three times as wide as the others; shoulder keel duplex, the posterior cord most 
prominent, the anterior, closely adjacent, less so; in front of these, extending to 
the canal, is a series (five on the penult, eighteen on the last whorl) of similar but 
less prominent, subequal, and subequidistant cords, with numerous smaller inter- 
calary threads, the interspaces wider than the primary cords; from the shoulder to 
the periphery on the last whorl are (on the type about fourteen) numerous obseure 
narrow vertical riblets extending to but not over the base, but not nodulating 
the superincumbent cords; there are also numerous very fine, slightly prominent 
lines of growth which tend to roughen the spiral sculpture; aperture short, wide; 
outer lip (defective) thin, simple; body with the sculpture erased, polished, milk- 
white; pillar very short, gyrate, almost pervious; canal very short and wide. 
Lon. of shell, 27; of last whorl, 16; of aperture, 12; max. diam. 12 mm. 
U. 8. S. “ Albatross,” station 3413, near the Galapagos Islands, in 1360 
fathoms, ooze, bottom temperature 36° F. U. 8. N. Mus. 123,111. 
A form of problematical relations, perhaps least out of place here, until more 
is known about it. 
