126 A NATUBALIST IN CELEBES ch. vi 



The Alcyonarian polypes can be readily and easily dis- 

 tinguished from the Zoantharian polypes. Whilst the 

 Zoantharian polype possesses simple finger -like tentacles, 

 the Alcyonarian polype's tentacles are invariably provided 

 with a number of small processes or pinnse ; they are in fact 

 feathered or pinnate tentacles. The Alcyonarian polypes, 

 moreover, have without exception eight tentacles, no more, 

 no less ; the Zoantharian may have very many tentacles, or 

 in some cases only ten or twelve, but rarely eight. 



Nearly all the Alcyonaria possess the calcareous spicules 

 characteristic of the order. Heliopora, a few of the stolon- 

 ifera, and some of the pennatulids or sea-pens, are the only 

 exceptions. The organ-pipe coral and the precious coral are 

 the only two in which the spicules become fused together 

 to form a solid skeleton. 



Besides the Zoantharia and the Alcyonaria, some 

 members of the order of the Hydrocorallinse form large 

 masses of calcareous skeleton, viz. the Millepores, which 

 may be ramified or plate-like in form. They may be dis- 

 tinguished from all others by the fact that the pores are 

 very small and arranged in systems, seven or eight smaller 

 pores surrounding a somewhat la.rger one in each system. 

 The smaller pores (dactylopores) shelter the small tentacle- 

 like zooids which catch the food, the larger pores (gastro- 

 pores) shelter the stomach zooids which digest it. The 

 natural history and structure of these forms have been so 

 well described by Prof. Moseley (51), who first discovered 

 their true affinities, that it is not necessary for me to again 

 describe them. 



To this order also belongs Distichopora, a beautiful 

 purple, and in some cases red hydrocoralline, common on 

 many reefs, but it is rarely found upon the shores of Talisse. 



The Bryozoa or Polyzoa too sometimes build beautiful 

 basket-like skeletons of lime, but as these do not form a 



