SP. T. A, STEPHENSON 
than simple, but that is inevitable in a large and very old 
group. 
6. It seems fair to suggest that the principles advocated 
and put into practice here might with advantage be applied 
to other animal groups (e. g. Gastropods and Lamellibranchs). 
It is not for a moment implied that the classification of animals 
as at. present understood does not group them correctly, speaking 
broadly and of the main groups; but that it needs revision 
and supplementing on the plan suggested, especially in the 
cases of some of the sub-groups, the classification of which 
sometimes seems tentative and not very clear. It appears 
that nearly eneugh data are now collected about animals to 
permit of entry on a new phase in the history of classification. 
It is becoming evident, with regard to species for instance, 
that some new system will shortly have to be devised which 
will more adequately represent their inter-relations, and allow 
for the idea of interlacing systems of concentric circles with 
the characters of the central imdividual in each system as 
those of the species, which has grown up. Some new conception 
will probably work itself out about classification in general 
also, and the revision of some groups in accordance with ideas 
advocated here is suggested as a small beginning along the 
road—a beginning which may possibly lead to further steps 
in the realization of the new conception. If it prove to be 
a blind alley, that conclusion should not take very long to 
emerge. 
7. SHORT GLossaRy. 
This is not in any way a complete glossary, but is meant for 
use in connexion with a few terms which more than most seem 
to require definition, for convenience in using the paper. 
Acontia.—Slender white or coloured threads attached 
to the borders of the mesenteries in some families of Actiniaria, 
just below the mesenterial filaments. They are loaded with 
nematocysts, and can be protruded through the mouth, and 
in some cases also (accidentally) through pores (cinclides) in 
the body-wall, for purposes of defence or to paralyse prey. 
Histologically they differ from mesenterial filaments. 
