300 CLASSIFIED RESUME OF ORGANISMS OBSERVED 

 'Phylum CHAETOGNATHA 



Arrow worms were seen in great numbers upon every 

 dive, and at all levels. The longest measured about two 

 inches. All of those which could be closely observed were 

 colorless or white, even at the lowest levels. In our trawling 

 nets the scarlet species are usually not taken above 3600 

 feet, and so it is not surprising that we saw none of them. 

 I could never catch clear views of the lateral pairs of fins, 

 but a number of times the brown bristles around the mouth 

 stood out sharply in the beam. No hint of luminescence 

 was ever observed, although one good-sized worm had 

 obviously just swallowed a luminous animal. The worms 

 looked like little white threads, shooting vertically upwards 

 and downwards through the water as often as horizontally, 

 and, like true plankton, they never seemed to make much 

 actual progress. At the greater depths there was no decrease 

 in their activity. The electric beam apparently did not af- 

 fect them. Two or three hundred arrow worms is the 

 usual number taken in a single trawling net, drawn 

 through the water for four full hours. Whenever I 

 switched on the bathysphere's beam, if my attention was 

 not distracted by some more important creature, I could 

 almost always see arrow worms, by shortening the focus 

 of my eyes. 



