OLASSIFICATION OF ACTINIARIA 503 
all of the endocoels, (xiii) more tentacles than one in connexion 
with some or all of the exocoels, (xiv) permanent tentacle- 
bearing arms of the oral disc. 
This is of course an incomplete list, but other characters 
not needing special mention here will reveal themselves 
in their respective contexts. None of the characters can be 
treated in an absolutely hard-and-fast way, and may need 
special consideration in special cases. Of those listed, nos. iv 
and villi affect genera more than families, but are interesting 
even if their presence or absence does not in itself determine 
the fate of a given form. No. vi has to be taken in connexion 
with the fact that sphincterless forms have to be included 
sometimes with forms which have a mesogloeal sphincter, 
sometimes with those possessing an endodermal one, or else 
alone, according to the sum of their other characters. 
Characters such as presence or absence of brood-pouches are 
not of much classificatory use. 
There are many other things involved in classifying Anthozoa 
which will be pointed out in due course, but a few need special 
mention ; they affect most, on the whole, groups larger than 
families. These may be taken one at a time. 
(i) Presence or absence of ciliated tracts on 
the mesenterial filaments. These ciliated ‘ tracts’ 
or ‘pads’ (Flimmerstreifen of German authors) are 
very definite structures, and their presence or absence seems 
to be one of the soundest indications we have of difference of 
tendency between one group and another. It forms also an 
easily-made-out character and one to which there is hardly 
any of the usual objection of intermediate conditions between 
presence and absence. ‘Their loss, as I conceive it (or their 
non-development if it were that), by the corals and by certain 
anemones seems to constitute a very distinct evolutionary 
step, which may be seized upon for purposes of classification. 
Its usefulness both as a clue and as a sound distinction has been 
somewhat swamped by the amount of attention which the next 
character has absorbed ; but I propose here to lay a good deal 
of stress upon it as being more valuable than no. 11. The 
