CCELENTERATA : HYDROCORALLIN^. 



147 



surround these in definite systems (fig. 65, a and b}. The 

 dactylozooids have no mouth, and are long and slender, carry.- 



Fig. 64. A, Portion of a mass of Millepora alcicornis, of the natural size : 

 of the same, cut open vertically to show the larger tabulate tubes (p p), 

 spongy coenosarcal skeleton (c c), enlarged ; C, Small portion of the surface, enlarged 

 to show the larger and smaller openings (// and c') inhabited by the different zooids, 

 and the reticulated calcareous tissue of the skeleton ; D, One of the tentacular poly- 

 pites, enlarged, showing two whorls of knobbed tentacles. (A, B, and C are after 

 Milne-Edwards and Haime ; D is after Martin Duncan and Major-General Nelson.) 



ing on their sides numerous short clavate tentacles. They per- 

 form the functions of prehension for the colony, and supply 

 food to the stomach-bearing gastrozooids, by which the work 

 of digestion and assimilation is carried on. The nutritive fluid 

 elaborated by the latter is distributed throughout the entire 

 colony by means of branched coenosarcal canals, which ramify 

 in every direction through the spongy tissue of the skeleton. 

 The reproductive process in Millepora is still unknown. 



Still more remarkable than the Millepora are the singular 

 organisms forming the family of the Sty laster idee , which have 

 hitherto been regarded as Corals, but which have been shown 

 by Mr Moseley to belong to the Hydrocorallince. The skeleton 

 of the Stylasteridce (fig. 66) is calcareous, more or less branched, 

 forming a dendroid or flabellate expansion, and exhibiting 

 upon the surface, or on its sides, small rounded apertures, 

 which are usually intersected marginally by radiating partitions 

 or "septa," and thus simulate the "calices" of an ordinary 

 sclerodermic coral. In other cases, the skeleton shows a 



