454 Birge—Vertical Distribution of Pelagic Crustacea. 
In Table J the column headed “variation” shows the average 
departure of a single observation from the mean. The column 
headed “per cent. ” shows the average per cent, which the num¬ 
ber obtained from any given level constituted of the total num¬ 
ber caught. It is not exactly the same as that given in the 
preceding tables since only the complete series could be used in 
computing it. The next column gives the variation in per 
cent, of the whole number caught. Thus in Period III the 
catch from the 0-3 m. level was on the average 44 per cent, 
of the entire number with an average departure of 9 per cent., 
or from. 35 per cent, to 53 per cent. Succeeding columns show 
that the range was from 74 per cent, to 31 per cent. The day 
and hour of maxima and minima are given to show the irregu¬ 
larity of distribution. The averages for the month are not 
given because of the increase or decrease of the number of crus 
tacea. 
