6o OUR COMMON BRITISH FOSSILS. 



abundant Silurian coral {Favosites Gothlandica)^ that 

 the coral-pipes — as we may call them — are separated 

 into horizontal chambers. The walls are perforated, 

 as they are in some of the Alcyonaria, possibly for 

 transverse canals. It will also be seen that the interiors 

 of the corals are not radiated — that is, have not those 

 vertical plates springing from the walls which are 

 called septa ; or, if they are present in Tabulate corals 



Fig. 39. — Millepora akicornis, a recent Hydrozoan Coral (Bermudas). 



they are very feebly marked. This general absence 

 of septa is the leading distinction of Tabulate corals. 

 Professor Mosely thinks that most, if not all, of this 

 group are in reality not Zoantharians, or true corals, but 

 Alcyonarians, of which the recent common Organ-pipe 

 coral {Ttibipora nmsica) is the best example. Some 

 of the so-called corals, as the Millepores, he proved 



