CLASSIFICATION OF ACTINIARIA 549 
filaments ’, ‘ presence of basilar muscles’, ‘ absence of ecto- 
dermal muscle in body-wall ’, ‘ presence of not more than one 
tentacle per exo- and endocoel’, and so on, could be added 
where suitable ; but the addition of all these where not strictly 
required for present purposes would be needlessly complicating 
—it is mentioned only to show that the lists could be expanded 
rather than otherwise. 
I should like to repeat here a remark made in Part I, to 
the effect that the arrangement suggested cannot be validly 
criticized on the ground that in some cases there are only one 
or two differences between two given families. Provided 
that the differences are good ones, this is all right—if families 
be fused up on that principle it is soon found that the whole 
Actiniaria will go into one or two collections, and classification 
breaks down altogether. The very fact that the families form 
enough of a series to have few differences sometimes, supports 
the idea that they represent relationships truly. 
If sums-of-characters for groups of wider inclusion than 
families be now taken, the difficulty of course arises that 
they can be made less absolute, because in some cases there 
are one or two exceptions to almost everything among large 
series of anemones, and this is the same whatever classification 
be adopted. It must therefore suffice to make definitions 
of tendency rather than of exclusive fact, in some cases. 
GROUPS LARGER THAN FAMILIES. 
Here the wider groups will be taken first. 
Class ANTHOZOA. Sub-classes included: Cerianti- 
patharia, Octactiniaria, Zoanthactiniaria. 
Common characters or tendencies, 14. 
Coelenterata with (i) no medusae, (ii) ‘ hydroid-generation ’ form, 
(ili) nematocysts, (iv) characteristic muscularity as compared with 
Hydrozoa, (v) bilateral symmetry typically, (vi) no primary cruciform 
symmetry like that of Scyphozoa, (vii) mesenteries, (viii) no septal 
funnels, (ix) no endodermal tentacles, (x) mesenterial filaments, 
(xi) endodermal gonads borne on the mesenteries, (xii) an actino- 
pharynx, (xiii) no canal-system comparable to that of a Seyphozoan, 
(xiv) no specialized sense-organs in adults. 
