568 T. A. STEPHENSON 
confirmation in a way that an artificial system of unit-characters 
cannot do—it justifies and bears out the instinct. The summa- 
tion principle also enables the family to be used definitely 
as the expression of a step in the evolution of any set of forms, 
and the classification represents evolution of whole anemones, 
not of their sphincters or tentacles only. It also provides 
evolutionary hints which could not otherwise come to light, 
and which, given a general idea of group-evolution, help to 
confirm and enlarge it. The general idea itself can grow from 
a comparison of early and advanced forms, embryology, and 
so on. From working through a whole group in such a way it 
does seem possible to get a glimpse of the rhythmical develop- 
ment of the life in the creatures, expressing itself in the various 
ways at its disposal and unfolding along various lines. It 
should be noted that im dealing with a group as plastic as 
Actiniaria, it 1s often necessary to define differentiation 
of tendency without too much insistence on hard and fast 
divisions without qualification or exception. 
3. The classification worked out on the above lines, in this 
paper, is as follows. For definitions of the groups and families, 
and for limitation of the sense in which they are taken, refer- 
ence should be made to the portions of the paper where these 
things are dealt with. I have accepted the arrangements of 
Bourne and Carlgren as regards sub-classes of Anthozoa ; 
and that of Bourne for orders and sub-orders. The tribes, 
sub-tribes, families, and genera have, however, been largely 
revised in this paper. I have kept as near to Carlgren’s tribes 
and sub-tribes as I felt possible, and have throughout used old 
names where I could; but the sense of his groups has been 
altered and they have been added to, and many of the families 
more narrowly limited, so that the old names take on a new 
meaning. 
CLass ANTHOZOA. 
Sub-class 2. OCTACTINIARIA. 
Sub-class 1. CERIANTIPATHARIA. 
{Subclass 3. ZOANTHACTINIARIA, 
