2 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 19 



During the first part of the operation, a series of four or five screens 

 was used on the boat. These screens measured 18 by 24 inches and were 

 made of stainless steel fitted with a brass mesh that varied from a coarse 

 one of 12 meshes, through 16, 20, and 24 meshes to the inch. When much 

 rubble was present in a sample, a coarser screen was placed over the 

 others to expedite the sorting of the finer materials. The mud was washed 

 through the screens with the aid of seawater hoses. The process was slow 

 and physically tiring. As harsh sprays were found to damage soft-bodied 

 animals, the use of nozzles on hoses was impracticable. Lighter, finger- 

 controlled sprays were laborious but resulted in better preservation of the 

 animals. 



The methods of washing and clearing of fine debris were considerably 

 improved when larger screens (figs. 14-16) with greater range in mesh- 

 size were introduced. These larger screens are now mounted on a shaker 

 device (see fig. 16 and Description of Equipment, below) which permits 

 the flow of materials through them without damaging the specimens. 

 The seawater comes through a system of shower-sprays, and the amount 

 and force of the sprays can be controlled through valves. Many of the 

 smaller animals that had become enmeshed around the wires of the 

 screens, had formerly to be washed or picked oiif separately ; now they 

 are largely disentangled with the aid of an air hose that causes them to 

 drop to the retaining sack (fig. 23). The removal of the washed and 

 cleared animals from the screens was at first performed by raising the 

 entire screen and washing the contents into a large pan or tub. This 

 method has been improved so that the contents are removed without 

 much lifting. 



The Velero IV has provided an excellent base from which a grab, 

 called by its manufacturer the Hayward-orange-pecl bucket (known 

 below as the orange-peel grab), of about two cubic feet capacity (see 

 figs. 5-8 and Description of Equipment, below), can be suspended. A 

 second larger one, the Campbell grab (figs. 17-20), named for its de- 

 signer, Alex Campbell, was introduced in April, 1954, and found more 

 effective in some kinds of bottoms. For each sample, the living metazoan 

 animals are sorted out. Many of these have now been identified, counted, 

 and charted. Since ultimate results can be based only on final counts 

 of heads or some other unit parts of living specimens, all estimates should 

 be regarded as minimal. There are, necessarily, losses of unmeasurable 

 amounts, resulting from the various stages through which each sample 

 must be processed. 



