The Comatulids of Torres Strait. 113 



theless it was clear that long arms in front, short arms behind, gave the 

 normal method of progression. It may be a fair inference that the 

 asymmetrical condition of the arms is the result of selection, since it 

 is possible that long arms would be better for pulling and short, stout 

 arms for pushing. But it is no doubt true that there are very diverse 

 interpretations of the matter possible, and it is no part of my purpose 

 to discuss the subject here. The statement of the facts given above 

 is beyond dispute, however. 



Locomotion in all the comatulids observed at Mae'r, whether swim- 

 ming or creeping, invariably takes place with the oral surface upper- 

 most. If dropped in deep water with the mouth down they commonly 

 righted themselves before reaching the bottom. If not, or if placed 

 on the bottom with the mouth down, they slowly but surely turned 

 over before attempting to either swim or creep. The process of turning 

 over is essentially the same as in a starfish. That is, a group of arms 

 begins the task and continues gradually lifting up one side until the 

 arms of that side can be bent back far enough over and beyond the 

 aboral surface to secure a hold. Then by their pulling and the pushing 

 of the arms opposite to them, the disk is righted. The process seems 

 a tedious one and is probably not often necessary in the normal life 

 of comatulids on the reef. 



Particularly interesting is the question of how much these comat- 

 ulids move about under the natural conditions of their life, but no 

 satisfactory evidence on the point was secured. On one occasion a 

 dozen healthy comatulids of four species were "planted" on a part 

 of the reef where no crinoids were living. Twenty-four hours later 

 they had all disappeared and no trace of them could be found in the 

 neighborhood. But as there had been a strong wind and much surf 

 during the night, they may have been simply swept away. On another 

 occasion 10 large comatulids were carefully located around the margin 

 of a rock-fragment about a meter in diameter. Circumstances, includ- 

 ing unfavorable tides, made it impossible to visit the spot again for a 

 week. Then it was found that more or less sand had washed in around 

 the rock and the comatulids were apparently gone, but again there 

 was doubt what part the surf and strong tidal currents may have 

 played. Crinoids dropped beside the live-car, on reaching the bottom, 

 began at once to move away and continued moving, usually in a fairly 

 straight line, until they reached a rock beneath which they could find 

 shelter, but it was not possible to determine their ultimate resting-place. 



During these experiments I was much struck by the attitude of 

 fishes towards the crinoids. Fishes of many species were abundant 

 in the water just outside the reef and their movements were easily 

 noted. Any object dropped in the water at once attracted their 

 attention and if edible was nibbled at or seized outright. Comatulids 

 were always noticed, but were never touched either in the water or 



