2 University of California Publications in Zoology. [Vol. 8 



an ordinary 000 surface net and with the Kofoid closing net of 

 000 mesh. The diameter of aperture of the former was 97.5 cm., 

 that of the latter was 18.5 cm. I have attempted to make up for 

 this difference in area of aperture in the following way. The 

 average number of animals taken by several hauls with the clos- 

 ing net at a certain depth and within certain time limits, was 

 standardised to a haul one hour in duration; this number was 

 multiplied by 28 since that represents the ratio between the 

 areas of the apertures of the two sorts of nets. It may be said 

 that the result gives numbers that seem far too large, and that 

 the method of correlation employed is very rough at the most 

 since it does not take into accoinit such factors as the rate and 

 distance of hauling, filtering capacity and variations in water 

 pressure. The following tabular view of the more general data 

 for the hauls that are concerned in this discussion may be useful. 



