248 ACTINOZOA. 



13. Recent Actinozoa. — 



Except the Rugosa, Tubulosa and Thecidce, 

 all the orders and families of the sub-kingdom 

 Coelenterata have living representatives. The 

 names of the recent genera are too numerous to 

 be here mentioned. Many of them have already 

 been indicated in those parts of the work devoted 

 to the study of their classification. 



The systematic form under which we have 

 sought to exhibit the above selection of facts 

 touching the general relations to time of the 

 several groups of Corals must not lead the student 

 to repose too much trust in a record confessedly 

 so imperfect, or regard it as aught else than, in 

 the strictest sense, provisional. In particular it 

 would appear from certain investigations, not yet 

 fully published, that the supposed line of demar- 

 cation between the Paleozoic and Neozoic Coral 

 forms does not really exist. The entire subject, 

 like many others discussed in the preceding 

 pages, still offers a wide and richly promising 

 field for future inquiry. 



