CLASSIFICATION OF ACTINIARIA 495 
of species the variation of the different anatomical criteria 
of distinction may be so wide, and the limits of specific varia- 
tion so little known, that to go beyond the genus is little more 
than guess-work ; especially when one thinks of the modifica- 
tion caused to certain characters by mode of preservation, 
degree of contraction or distension of the animal, age, reproduc- 
tive condition, locality, and other things. ‘Two paths there 
are here which need following. Firstly, a large number of 
anemones should be collected (some belonging to stable and 
some to unstable species, and representative of various families) 
in cases where it could be positively certified that all individuals 
collected for any one species were undoubtedly the same. 
These should be preserved in different ways and states, and 
a study made which would reveal the limits of specific varia- 
tion—or it might prove that sometimes there are no limits. 
Even after this, many descriptions would need supplementing 
before a revision of species within the group could be 
attempted. The second path is the study of nematocysts ; 
it may prove that measurements of these will provide 
clear specific distinctions. 1 believe Professor Carlgren will 
bring forward a good deal of evidence in this connexion, 
I have not been able myself to give this point much attention, 
but what I have done rather suggests that the size of the cells 
is too variable and too similar in clogely-related species to help 
us. Pax has a note on this in his paper on the ‘ Family 
Actiniidae’, pp. 80-2. At least it becomes evident that 
species-identification from preserved material, with certainty, 
is going to be extraordinarily laborious. It would probably 
better repay effort to take more notice of the living animals, 
for here one’s experience suggests that species-identification 
from colour and habit in life would usually be easy and sure. 
Experience is leading me to the view that among these low 
and plastic forms a species may have its peculiarities of organic 
constitution at an early stage of the development of their 
expression, such expression having affected colour scheme and 
general facies of the living animal but not necessarily to any 
extent the internal anatomy which can be studied in preserved 
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