204 



ACTINOZOA. 



the thecae of the separate corallites do not become 

 lost in the surrounding coenenchyma. In the 

 Poritidce, on the contrary, such fusion always 

 takes place, and the septal system, instead of 

 forming distinct plates, consists wholly of more or 

 less definite series of trabiculae. The entire 

 corallum, in like manner, appears to be made up 

 of a spongy, reticulate sclerenchyma. 



The next division, Tuhulosa, contains only a 

 single family, Auloporidce ; and this but two 



Fig. 36. 



ZoANTHAEiA scLEEODERMATA : — a, corallum of TurbinoUa 

 costata; b, the same, in transverse section, showing the columella, 

 septa, theea, and costae ; c, part of corallum of Aulo^ora tubsfor- 

 mis, (All, except c, magnified), 



genera, Fyrgia and Aulopora, in both of which 

 the corallite, while destitute of tabulae, has its 

 septal system indicated by faint markings along 

 the inner surface of a comparatively smooth tube. 

 Fyrgia is simple, though having a distinct epi- 

 theca. In Aulopora the somewhat remote coral- 

 lites are connected by means of a basal creeping 

 ccenenchjTna. (Jig. 36, c.) 



The four last families of Zoantharia constitute 



