538 T. A. STEPHENSON 
§ P. The. Groups larger than families, and the 
Arrangement of the families within these 
Groups. 
At this point discussion becomes more difficult and more 
dependent upon individual opinion. It may be simplest to 
start with the class Anthozoa and work downwards. Neither 
nomenclature nor main subdivisions are my special concern 
here, but probably no one will object to one of the following 
alternatives, whatever names be preferred. 
Bourne’s division is 
Sub-class 1. OcvracrrintaRtia. 
Sub-class 2. CERIANTIPATHARIA. 
Sub-class 3. ZOANTHACTINIARIA. 
Or one could use 
Sub-class ]. OcTACTINIARIA. 
Sub-class 2, CERIANTHARIA. 
Sub-class 3. ANTIPATHARTA. 
Sub-class 4. ZOANTHACTINIARIA. 
Hither of these is a good arrangement, probably, leaving aside 
the vexed question of Tetracorallia—it has recently been 
suggested that these may have something to do with the 
Endocoelactid type of structure. 
The next step is the subdivision of the Zoanthactiniaria. 
Few will object to having the Zoanthids as a separate set 
among them, and although Edwardsiids are sometimes included 
with ordinary anemones, Bourne has recently shown that 
they must rank as a distinct group equal to that contaiming 
the Zoanthids. So the Zoanthactiniaria may be divided into 
three or four, with a number of common tendencies (see p. 651). 
Bourne subdivides thus : 
Order 1. ZOANTHINARIA, 
Order 2. EDWARDSIARIA. 
Order 3. DODECACTINIARIA. 
His order Dodeecactiniaria includes the sub-orders Actiniaria 
and Madreporaria. Carlgren, however, divides — slightly 
differently. 
