The Productivity of Fish Food in Oneida Lake 93 



vicinity of Lower South I>ay are also included in the dis- 

 cussion. 



Life on the Boulder and Gravel Bottom, As already 

 explained, the amount of life on the boulders was ascertained 

 by measuring a number of boulders and carefully removing 

 and preserving all of the life on them. Forty-six such units 

 were examined, the average area being 4^2 by 3 inches, or 

 I2,y> square inches. Of animal life the total for the 46 units 

 was 159 mollusks and 325 associated animals, or 3.45 mollusks 

 and 7.06 associated animals per unit area. On the gravel 

 bottoms, which were closely associated with the boulder bot- 

 toms, 34 units of 16 square inches area were examined; the 

 total molluscan life on these units was 306 and the associated 

 animal life 355, or an average of 9. mollusks and 10.44 asso- 

 ciated animals per unit area. Combining the average life of 

 both boulder and gravel areas we have, after reducing the 

 boulder area of 13^ square inches to the gravel unit of 16 

 square inches, 6.54 mollusks and 9.40 associated animals per 

 unit area four inches square. The boulder and gravel areas 

 cover 20 acres and there is thus calculated, on the basis of the 

 average of 80 samples, a population of 51,341,558 mollusks 

 and 73,758,405 associated animals. The total animal popula- 

 tion is estimated at 125,099,964* individuals in the 20 acres 

 covered with gravel and boulders (see figures 21-24, which 

 show the approximate number of animals in unit areas of 

 boulder, 13^ inch unit, and gravel, 16 inch unit, bottoms). 



In the tables of animal life on the boulder and gravel bottoms 

 (Nos. 16, 17) it will be noted that on boulder bottoms the 



* The computations for the resuhs recorded above are as follows : 

 43.560 (sq. ft. in acre) X 144 (sq. inches in foot)= 6,272,640 square 

 inches in one acre; X 20 acres = 125,452,800 square inches -^ 16 (sq. 

 inches in unit a rea)= 7,840,800 unit areas in 20 acres; X 6.54 mollusks 

 per unit area = 51,341,588 mollusks. 7,840,800 unit areas X 9.40 associated 

 animals per unit area =^ 73,758,405 associated animals -f- 51,341,558 = 

 125,099,964, the total macroscopic animal population in 20 acres. 



In the original computations, the averages of the mollusks and of the 

 associated animals were carried out to the third decimal point (as 6.548 

 and 9.407 above), and the calculations of population are based on these 

 figures. In all of the computations of the macroscopic fauna published 

 in this paper, the third decimal number has been omitted but the multi- 

 plication totals are based on these three decimal figures. 



