REMINISCENCES OF HUXLEY 223 
of parts performing different functions; (2) Ccelente- 
rata, in which there is a simple differentiation between 
the inside, which accumulates energy, and the outside, 
which expends it; and (3) Coelomata, in which the in- 
side contains a more or less elaborate system of distinct 
organs devoted to nutrition and reproduction, while the 
outside is more or less differentiated into limbs and 
sense organs for interaction with the outer world. 
Though not yet an evolutionist, Huxley could not re- 
press the prophetic thought that Ccelenterata are 
‘ancient survivals, representing a stage through which 
higher animal types must once have passed. 
As further elaborated by Huxley, the development 
above the ccelenterate stage goes on in divergent lines; 
stopping abruptly in some directions, in others going 
on to great lengths. Thus, in the direction taken by 
echinoderms, the physical possibilities are speedily ex- 
hausted, and we stop with starfishes and holothurians. 
But among Annuloida, as Huxley called them, there is 
more flexibility, and we keep on till we reach the true 
Articulata in the highly specialized insects, arachnoids, 
and crustaceans. It is still more interesting to follow 
the Molluscoida, through which we are led, on the one 
hand, to the true Mollusca, reaching their culmination 
in the nautilus and octopus, and on the other hand to 
the Tunicata, and so on to the vertebrates. 
In the comparative anatomy of vertebrates, also, 
Huxley’s achievements were in a high degree original 
and remarkable. First in importance, perhaps, was 
his classification of birds, in which their true position 
and relationships were for the first time disclosed. 
Huxley showed that all birds, extinct and living, must 
be arranged in three groups, of which the first is repre- 
