4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



Isaacs-Ejdd midwater trawl: Twenty-one Isaacs-Kidd mid- 

 water samples (IK) collected on Anton Bruun Cruise 6 were examined 

 and 10 to 70 copepods removed from each sample. The larger 

 and deeper Hving species not usually collected in small vertical 

 nets were selected from the trawl sample. The cod end of the trawl 

 was made of number 2 mesh net (.366 mm). The maximum depth 

 of trawHng was determined from a time-depth recorder or calculated 

 from measurements of length of wire-out vs. wire angle. Although 

 a catch divider (Foxton, 1963) was attached to the end of the trawl, 

 it apparently did not operate properly. Consequently, no attempt 

 is made to discuss the vertical distribution of the species collected 

 by the midwater trawl. A total of 797 adult copepods (113 species) 

 were identified in these trawl samples. 



Nansen vertical net: Twenty-four collections were also obtained 

 on Anton Bruun Cruise 6 by a modified Nansen vertical net (NV). 

 This net is similar to the one described by Currie and Foxton (1957) 

 except that a flow-meter was mounted within the mouth of the 

 net and a time-depth recorder (Benthos Mfg. Co., North Falmouth, 

 Mass.) was attached to the weight below the cod end of the net. 

 The net was made of number 6 mesh (.239 mm aperture). The 

 samples from the following depth intervals are considered here: 

 2000-1000 m, 3000-2000 m, and 4000-3000 m. The time-depth 

 recorder was equipped with a magnetic switch. Upon closure of 

 the net, this switch activated a stylus that marked the recording 

 chart. The maximum depth reached by the net and the depth 

 of net closure was thus indicated on the chart. Since the speed 

 of ascent of the net (60 m/min) and speed of descent of the messenger 

 (200 m/min) that triggered the release and closure of the net was 

 known, it was also possible to compute the depth of closing. In 

 actual practice the depth of closing was clearly indicated in most 

 cases by a severe jerk of the hydrographic wire when the throttHng 

 Hne pursed the net. When this occurred, the amount of wire out 

 was recorded. Good agreement was found between the com- 

 puted and actual depths of closure. The corrected depths are 

 given in table 1. The method of measuring the volume of the NV 

 samples and treating the copepods are the same as discussed in an 

 earher paper (Grice and Hulsemann, 1965). A total of 1740 adult 

 copepods (194 species) were identified in these samples. 



Contaminants: Twenty-six species of copepods collected by the 

 NV net, which we feel may possibly have entered the net at 

 shallower depths than those indicated, were found in many collec- 

 tions. These species, fisted below, are in addition to those previ- 

 ously considered as contaminants in NV samples collected in the 

 northeastern Atlantic Ocean (see Table II, Grice and Hulsemann, 



