MATERIAL AND METHODS 167 



Normally seven hauls were made at all these stations, from 50-0 m., 100-50 m., 250-100 m., 

 500-250 m., 750-500 m., 1000-750 m. and 1 500-1000 m. Allowance has been made for these varying 

 lengths of haul in the vertical distribution charts for three species collected along the o° Line. A haul 

 of 250 m. has been taken as the standard, and the number of specimens collected in the 50-0 m. and 

 100-50 m. hauls multiplied by 5, in the 250-100 m. hauls by 5/3, and in the 1500-1000 m. hauls by \. 



(a) (b) 



Text-fig. 4. Greenwich Meridian (o° Line), (a) Sts. 2010-27, March-April 1937; Sts. 2492-2501, November-December 

 1938; Sts. 2530-47, January 1939. (b) Sts. 1772-82, May-June 1936; Sts. 2311-22, April 1938; Sts. 2355-61, 2385-93, 

 2424 and 2425, July-September 1938. 



Each amended number is plotted in the mean position of depth for each particular haul. The effect 

 is that the plotted numbers represent the relative density of the population per unit volume of water 

 in that part of the column sampled in each haul. The actual numbers of specimens caught by each 

 net are given in Appendix I. The N 70 V samples from the o° Line collections were taken in three 

 hydrological zones over a distance of approximately 2160 nautical miles and provide quantitative 

 information on the distribution of the smaller polychaetes. 



In addition to the above samples material collected by N 100 B or N 70 B nets was examined 

 from the following stations on the o° Line: 1148, 1772, 2010-2027; 1813, 1815, 2322 (see 

 Appendix II). 



