THE DEPOSITS OF THE SEA-BOTTOM. 



19 



By this manner of proceeding we get the groups upon the whole best adapted for the examination. 

 The ingredients over o-z™ m are upon the whole too great to be examined by the microscope, but fit 

 for an examination by the magnifying glass; they contain no other siliceous organisms than sponge 

 spicules. The ingredients between o-5 ram and o-05 mm contain the minerals in the size best adapted for 

 microscopical examination; besides the sponge spicules are found of organisms only a single form of 

 Radiolaria. The ingredients from 0-05 — cro2 mm show the advantage that they contain almost all the 

 siliceous organisms within so small a space as possible whereby the examination of them is made 

 much easier. The minerals show nothing of special interest, being the same as those of the preceding 

 part. The ingredients under o - 02 mm contain all the clay, besides small mineral grains of no interest, 

 and finally fragments of sponge spicules, Radiolaria, and Diatoms, as well as whole individuals of a 

 few smaller forms of Diatoms. With regard to the parts containing lime, it is also especially fortunate 

 that the border has been placed at 0:5"™; all higher animal groups are found between the coarser 

 ingredients, coccoliths and the like between the finer; and the Foraminifera, that are of far the greater 

 importance, are divided into two groups, and these, as will be shown in a later section, are essentially 

 different with regard to their distribution. 



In the following table showing the results of the washing I have, for the sake of the survey, 

 taken each bottom-specimen for itself; otherwise I have followed the numerical order. 



Table showing the amount of carbonate of lime, and the different sizes of grains in the bottom-specimens. 



I. Shallow-water deposits (sand and clay). 



II. Gray deep-sea clay. 



3* 



