568 WORST JOURNEY IN THE WORLD 



feet, working by suction, by which they withdraw the 

 water inside a receptacle in the shell, thereby forming a 

 vacuum ; starfishes do the same. We found a species of 

 sea-urchin which had such large spines that they practi- 

 cally formed bars ; the spines were twice as long as the 

 sea-urchin and shaped just like oars, being even fluted. A 

 lobster grows by discarding his suit, hiding and getting 

 another, growing meanwhile. A snail or an oyster retains 

 his original shell, and adds to it in layers all the way down, 

 increasing one edge. But our sea-urchin grows by an incre- 

 ment of calcareous matter all round the outside of each 

 plate. As the animal grows the plates get bigger. 



There was a sea-cucumber which nurses its young, 

 having a brood cavity which is really formed out of the 

 mouth: this is a peculiarity of a new Antarctic genus found 

 first on the Discovery. It has the most complex water- 

 tubes, which it uses as legs, and a few limy rods in its soft 

 skin instead of the bony calcareous plates of sea-urchins 

 and starfish. After them came the feather-stars, a relic of 

 the old crinoids which used to flourish in the carboni- 

 ferous period, examples of which can be found in the 

 Derbyshire limestone ; and there were thousands of brittle- 

 stars, like beautiful wheels of which the hubs and spokes 

 remained, but not the circumference. These spokes or legs 

 are muscular, sensory and locomotive; they differ from the 

 starfishes in that they have no digestive glands in their 

 legs, and from the feather-stars in that they do not use 

 their legs to waft food into their mouths. Once upon a 

 time they had a stalk and were anchored to a rock, and 

 there are still very rare old stalked echinoderms living in 

 the sea. This apparently geological thing was found by 

 Wyville Thomson in 1868 still living in the seas to the 

 north of Scotland, and this find started the Challenger 

 Expedition for deep-sea soundings in 1872. But the 

 Challenger brought back little in this line. Most of the 

 species we found were peculiar to the Antarctic. 



There were Polychaete worms by the hundred, show- 

 ing the protrusable mouth, which is shoved into the mud 

 and then brought back into the body, and the bristles on 





