of Edinburgh, Session 1883-84. 
497 
mud brought up from great depths. The observations of Wallich, 
Huxley, Agassiz, Baily, Pourtal^s, Carpenter, Thomson, and many 
others, while not neglecting mineralogical and chemical composition, 
deal with this only in a subordinate manner. The small quantities 
of each specimen at their command, and the limited areas from 
which they were collected, did not permit the establishment of 
any general laws as to their composition or geographical and 
bathymetrical distribution. These early researches, however, 
directed attention to the geological importance of deep-sea de- 
posits, and prepared the way for the expeditions organised with 
the special object of a scientific exploration of the great ocean 
basins. 
The expedition of the Challenger ” takes the first rank in 
these investigations. During that expedition a large amount of 
material was collected and brought to England for fuller study 
under the charge of Mr Murray, who has in several preliminary 
papers pointed out the composition and varieties of deposits which 
are now forming over the floor of the great oceans. In order to 
arrive at results as general as possible, it was resolved to in- 
vestigate the subject from the biological, mineralogical, and 
chemical points of view, and M. Kenard was associated with Mr 
Murray in the work. In addition to the valuable collections and 
observations made by the “ Challenger,” we have had for examina- 
tion material collected by other British ships, such as the “Porcupine,” 
“Bulldog,” “Valorous,” “Nassau,” “Swallow,” “Dove;” and, 
through Professor Mohn, by the Norwegian North Atlantic Ex- 
pedition. Again, through the liberality of the United States 
Coast Survey and Mr A. Agassiz, the material amassed in 
the splendid series of soundings taken by the American ships 
“ Tuscarora,” “ Blake,” and “ Gettysburg,” were placed in our 
hands. The results at which we have arrived may therefore be said 
to have been derived from a study of all the important available 
material. 
The work connected with the examination and description of 
these large collections is not yet completed, but it is sufficiently 
advanced to permit some general conclusions to be drawn, which 
appear to be of considerable importance. In addition to descrip- 
tions and results, we shall briefly state the methods we have 
