of Edinburgh, Session 1881 - 82 . 
663 
Caebonate of calcium 32 72 per cent., consists of Coccoliths, 
Coccospkeres, Globigerinas, Pnlvinulinas, Orbulinas, Nodosarias, 
Truncatulinas, Nonioninas, &c. Fragments of Echini, Molluscs, 
Ostracodes, one or two Pteropod fragments. 
Residue 67*28 per cent., greyish-brown, consists of — 
Minerals [40-00], m. di. 0*1 mm., almost all angular; quartz, 
hornblende, augite, magnetite, volcanic glass, glauconite, feldspar. 
Siliceous organisms [5 *00] : Diatoms, Radiolarians, Sponge spicules, 
and a few glauconitic casts of Foraminifera. 
Fine washings [22*28] ; argillaceous matter with minute fragments 
of minerals and siliceous organisms. 
Remarks . — The larger portion of the mud was passed through fine 
approximate valuation, of which we will give the basis in our report. As it is 
important to determine the dimensions of the grains of minerals which consti- 
tute the deposit, we give, following the contraction m. di., their mean diameter 
in millimetres. This evaluation is made with the micrometer. We give next 
the form of the grains, if they are rounded, &c. , then follows the enumeration 
of the species of minerals and rocks. In this enumeration we have placed the 
minerals in the order of the importance of the role which they play in the 
deposit. The specific determinations have been made with the microscope, 
and with the aid of Nicol’s prisms, by parallel or convergent light. 
2. Siliceous Organisms . — The number between brackets indicates the per- 
centage of siliceous organic remains. We obtain it in the same manner as that 
placed after the word Minerals. The siliceous organisms and their fragments 
are examined with the microscope. We have also placed under this heading 
the glauconitic casts of the foraminifera and other calcareous organisms. 
3. Fine Washings . — We designate under this name the particles which, 
resting in suspension, pass with the first decantation. They are about 0'05 
mm. or less in diameter. We have not been able to arrange this microscopic 
matter under the category of Minerals, because at this small size it is impos- 
sible to determine the species. We have always found that the Fine Washings 
is in considerable quantity as the deposit passes to a clay, and it is from this 
point of view that the subdivision has its raison d'etre. We often designate 
the lightest particles by the name argillaceous matter, but usually there are 
associated with this very small fragments of indeterminable minerals, and 
fragments of siliceous organisms. The number within brackets which follows 
the words Fine Washings is obtained in the same manner as the similar 
numbers referred to in the two preceding paragraphs. 
These few words will suffice to render our descriptions intelligible. Greater 
details will be given, as already stated, in our larger work. We may add that 
in the majority of cases we have solidified the sediments and formed them into 
thin slides for microscopic examination, and that at all times the examination 
by transmitted light has been carried on at the same time as the examination 
by reflected light. Each description is followed by notes upon the dredging 
or sounding, upon the animals collected, and a discussion of the analysis 
whenever a complete analysis has been made. 
J. M. and A. E. 
