52 A NATURALIST IN CELEBES ch. hi 



In the neighbourhood of these bat and bird caves there 

 were several broad ledges of rock covered, of course, with 

 barnacles and limpets, but often bearing small shallow 

 pools containing specimens of the fauna and flora of the 

 sea-bottom. In one of these I obtained half a dozen 

 specimens of the curious barnacle Pollicipes ; in another I 

 found a few small specimens of the purple Distichopora. 

 As this was the first time — and, as it happened, the last — 

 I had found Distichopora, I was very anxious to see the 

 polypes alive and expanded, but I was disappointed, for they 

 were all retracted. I fancy that in these shallow pools the 

 polypes are generally expanded only at night or in the early 

 morning, for the sun soon raises the temperature of the 

 water to such a degree that their movements, if expanded, 

 would be sluggish and uncertain. The Distichopora does 

 not belong to the same class of the animal kingdom as 

 the ordinary corals. The animals which build up the vast 

 masses of madrepores, astraeas, and other reef-building 

 corals, are allied to the sea-anemones, but the animals 

 which build up the arborescent skeleton of Distichopora 

 and the great laminae of the millepores are more nearly re- 

 lated to the common fresh-water polype Hydra and its allies. 

 They exhibit, however, a very curious division of labour 

 in their colonies, as Professor Moseley discovered. Some 

 of them are simply stomachs for the reception and digestion 

 of food, while others are simply feelers for catching it. As 

 all the individuals of such a colony are united together by 

 a very complicated system of canals, this arrangement for 

 catching and digesting the food benefits all alike, and is no 

 doubt extremely efficient. 



The majority of the forms in these pools were, however, 

 true corals. I remember a beautiful piece of a coral called 

 Galacea, most splendidly decorated with bright-green ten- 

 tacles, and a mass of Astrsa whose polypes were marked 



