MUSEUM OF COMPARATIVE ZOOLOGY. 11 
extending between Hood and Chatham (287 fathoms) runs towards 
Barrington, and also separates that island from Chatham (Plate XI. 
Fig. 2). d 
On account of the small number of soundings, no attempt has been 
made to draw curves of depth on the chart of the Galapagos (Plate IV.). 
The structure of Albemarle, made up of a series of at least five vol- 
canic centres, with the adjacent Narborough, gives us an indication of 
the probable appearance of the central and western group of islands 
were they still active so as finally to become connected and form a 
huge island, with James, Indefatigable, Jarvis, Duncan, Barrington, and 
Charles as the culminating points of the plateau formed by the 100 
fathom line. We may therefore look upon the Galapagos Islands as a 
group of volcanic islands, gradually built up by successive flows of lava 
upon a huge mound, itself perhaps raised by the same agencies from the 
floor of the ocean; more active local flows in the same region having 
at special points built up more rapidly the northern group of islands, 
Wenman and Culpepper, and the two other groups of islands we have 
recognized. 
CHARACTER OF THE Bottom Deposits. 
We dredged frequently in most characteristic Globigerina ooze. On 
one occasion the trawl came up literally filled with masses of a species 
of Rhabdamina closely allied to R. lineata. 
It is interesting to note that, at two localities not far from the coast 
off Mariato Point, we came across patches of modern greensand similar 
in formation to the patches discovered off the east coast of the United 
States by the earlier dredgings of the Coast Survey, of Pourtalés, and 
of the “Blake.” (See page 5, Stations 3357, 3358.) 
Nearly everywhere along our second line of exploration, except on the 
face of the Galapagos slope, we trawled upon a bottom either muddy 
or composed of Globigerina ooze, more or less contaminated with terrige- 
nous deposits, and frequently covered with a great amount of decayed 
vegetable matter. We scarcely made a single haul of the trawl which 
did not bring up a considerable amount of decayed vegetable matter, 
and frequently logs, branches, twigs, seeds, leaves, fruits, much as during 
our first cruise. 
I was struck, while trawling on our second line between the Galapa- 
gos and Acapulco, to observe the great distance from shore to which 
true terrigenous deposits were carried. There was not a station there 
occupied of which the bottom could be characterized as strictly oceanic. 
