Methods of Counting and Computing the Crustacea. 433 



kind. This quantity was found by experience to be the most ad- 

 vantageous, since a greater number of animals was likely to cause 

 confusion and fatigue in counting, and a smaller number led to 

 loss of time. The trough thus filled was slowly moved through 



STATION UuC/t^ PtmtJ^ | 



DATE CLtCO. /, /tftf HOUR f/.J^. f. 

 SKY Ciic^L, WIND ft* &**>* TEMP./rf 

 DEPTH 0" 3 m. TOTAL DEPTH / f m. 



CATCH DILUTED TO £-V ccm. C^ 



Ccm. COUNTED *f . FACTOR 6 Z^ 



DIAPTOMUS l$.h ./*-*£ 

 CYCLOPS .$fc (JCU- 



DAPHNIA PULEX, var. PULICARIA 

 D. HYALINA . % . (j 

 DAPHNELLA BRACHYURA 

 LEPTODORA HYALINA 

 CHYDORUS SPHAERICUS 

 CORETHRA LARVAE 

 CHIRONOMUS LARVAE . 



Counted 



Total 



2.^2. 



/S7i 



/fro 



/olro 



? o 



— 



n 



/02. 



? 



2-/ 





Id 





/ 



Fig. 1. — Specimen Registry Card. 



the field of the microscope, one species was counted at a time, 

 and the number noted. When the entire quantity had been 

 counted the results were footed up and compared. In general 

 each of the countings showed closely corresponding results. The 



