DALL: MOLLUSCA AND BRACHIOPODA. 323 
U.5S.5. ‘ Albatross,” station 4649, between the Galapagos Islands and Sechura 
Bay, Peru, in 8. Lat. 5° 17’, and W. Lon. 85° 20’, 2235 fathoms, mud, bottom 
temperature 35°.4 F. U.S. N. Mus. 110,569. 
There is a minute chink behind the elevated edge of the columellar callus 
anteriorly, but no umbilicus. This appears to be the largest shell from so great 
a depth of water that has yet been collected; the depths noted by the ‘“ Chal- 
lenger ” are somewhat inexact, owing to the use of hemp rope in dredging, and 
nearly all excessive; but taking them at their face value, a Dentalium, a Chiton, 
and a Pleurotomoid shell alone were obtained from greater depths. 
Odcorys (Benthodolium) pacifica Dati. 
Plate 4, figure 7. 
Benthodolium pacificum Dall, Proc. U. 8. Nat. Mus., 1896, 18, p. 11. 
Shell resembling B. abyssorum Verrill and Smith, from the North Atlantic, 
from which it differs by its much more elevated spire with the same number of 
whorls, its smaller last whorl and aperture in proportion to the whole shell, its 
more slender pillar and larger umbilicus, and especially by having its spiral sculp- 
ture less crowded, and reticulated by narrow, flattened threads overrunning the 
spirals and in harmony with the lines of growth. Lon. of shell, 30; of last whorl, 
24; of aperture, 20; max. diam. 20 mm. 
U.S. S. “ Albatross,” station 3375, near Malpelo Island, Gulf of Panama, in 
1201 fathoms, ooze, bottom temperature 36°.6 F. 
U.S. N. Mus. 123,031. 
The operculum is narrower and less spiral than that of the Atlantic species. 
A fragment probably belonging to this species was also dredged at station 
3386, in 1067 fathoms, globigerina ooze, bottom temperature 37° F. 
The fine reflected outer lip of this species is obscurely ribbed like that of 
Hudolium, but the difference in the nuclear shell and in the operculum are quite 
sufficient to make the distinction between them easy. 
At station 3422, off Acapulco, Mexico, in 141 fathoms, mud, bottom temperature 
53°.5 F., a number of larval shells were obtained which appear to belong to a young 
stage of a species of Doliidae; even the genus cannot with our present knowledge 
be definitely determined. . 
Cypracidae. 
WRIEIVHA Gray. 
Trivia atomaria Dat. 
Plate 12, figures 8, 10, 11. 
Trivia atomaria Dall, Nautilus, Aug., 1902, 16, p. 43. 
Dredged in Panama Bay in 1888, in 18 fathoms, muddy bottom. U.S. Nat 
Mus. 109,206. 
This is one of the smallest species known. 
