EEPORT ON THE TETRACTINELLIDA, 
395 
By dividing the numbers in the first table by the corresponding numbers of the 
second, we obtain a fraction which represents the relative density of distribution of the 
group on the basis of unity. Thus, in the case of the Tetractinellida, the number in the 
first column of both tables is 16, so that the quotient to be placed in Table III. will be 1. 
Table III. 
I. 
0-50 
Fathoms. 
II. 
51-200 
Fathoms. 
III. 
201-1000 
Fathoms. 
IV. 
Above 1000 
Fathoms. 
Tetractinellida, .... 
1 
1T22 
0-6 
0-11 
Hexactinellida, 
1 
1-088 
0-581 
Monaxonida, .... 
1 
0-8 
0-6424 
0-126 
Cexatosa, .... 
1 
0-3 
0-1231 
Calcarea, .... 
1 
0-7707 
0-1 
These comparisons are rendered clearer by representing the proportion between the 
numbers of the columns by multiples instead of fractions of unity. Thus in the fourth 
column instead of OTl we place 1, and increase the contents of the other columns in pro- 
portion. 
Table IV. 
I. 
0-50 
Fathoms. 
II. 
51-200 
Fathoms. 
III. 
201-1000 
Fathoms. 
IV. 
Above 1000 
Fathoms. 
Tetractinellida, .... 
9 
11 
5-4 
1 
Hexactinellida, ' . 
1-72 
1-872 
1 
Monaxonida, .... 
7-92 
6-336 
5-048 
1 
Ceratosa, .... 
8-1 
2-437 
1 
Calcarea, .... 
10 
7-707 
1 
Somewhat is also to be learnt from the proportion of stations at which successful 
hauls were made. I therefore add a table in which the absolute number of successful 
stations is given in one line, followed by another in which the ratio of the number of 
successful hauls to the actual number of hauls made is given ; this ratio in the fourth 
column being taken as unity, the ratios in the remaining columns are shown as multiples 
of it, as follows ; — 
