206 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
As regards the deep-water species this is the first general report upon 
those obtained in the eastern Pacific, north of the Antarctic region prop- 
erly so called, and south of California, on the west coast of Middle and 
South America. The “Challenger” only entered this region for a very 
brief period, in which but a few hauls of the dredge were made, and the 
number of species of Mollusca then obtained was very small. A little 
dredging has been done by the various Antarctic expeditions en route, 
but in the area above indicated for the abyssal Mollusca the ** Albatross " 
had a practically virgin field. 
The littoral mollusk-fauna of the west coast of South America has 
been explored by D’Orbigny, Cuming, Hupé, C. B. Adams, Plate, Hi- 
dalgo, and several other naturalists, with a considerable literature as a 
result, Smith, Strebel, Mabille and Rochebrune, Couthouy, Gould, 
King, Philippi, and Melvill have investigated in more or less detail the 
shallow-water fauna of the Magellanic region, which is now becoming 
relatively well known; but these orarian species, with an interest all 
their own, have comparatively little affinity with those of the deeper 
waters beyond the hundred-fathom line. 
I have included in this report a general discussion of all the mollusks 
collected, with the exception of the nudibranchs, which were placed in 
the very competent hands of Dr. Rudolph Bergh of Copenhagen, and 
which were for the most part from comparatively shallow water. 
The brachiopods were individually few, but included several inter- 
esting new forms. 
To the discussion of the species I have prefixed a list of the mollusks 
and brachiopods of the deep sea actually known to have been obtained 
from the region indicated, In this list, for completeness’ sake, I have 
included the few species obtained by the “Challenger” and by other 
expeditions, but which were not collected by the “ Albatross.” 
Species not found at greater depths than 100 fathoms are not included 
in the list, with the exception of a few obviously benthal forms which 
seemed to have strayed into shallower water. There was much tempta- 
tion to include a certain number of deep-sea mollusks which have been 
dredged in the Pacific or Antarctic seas and which were known or sus- 
pected to have a wide distribution in the deep sea, in common with 
certain others which also do occur off the South American coast. But 
on reflection it was thought best for the usefulness of the list to restrict 
it to species actually obtained in the region referred to, taking nothing 
for granted, except where otherwise indicated. It is true that some 
abyssal species do have a most extraordinarily extended range, but it 18 
