6 BRITISH JURASSIC GASTEROPODA. 
essence of a question which has been frequently asked of late years. Those who 
ask such a question contend that, since the practical acceptance of the doctrine of 
Evolution by the scientific world, the old binomial system is insufficient for the 
requirements of biological knowledge. 
It will be remembered that an important congress of naturalists was held some 
time ago at the British Museum under the presidency of Professor Flower, for the 
purpose of discussing the subject of zoological nomenclature. All parties were 
well represented—uncompromising binomialists, limited trinomialists, and thorough 
trinomialists. As far as the philosophy of the subject in dispute went, it appeared 
to me that the trinomialists had the best of it; but when it came to a matter of 
policy and practice, the more conservative side had much to say in favour of the 
old method. In summing up, Professor Flower, who declared himself a limited 
trinomialist, said that distinctly defined species undoubtedly exist in great numbers 
owing to the extinction of intermediate forms; for such the binomial system 
offers all that is needed in defining them. But infinite gradations are being traced, 
both of present and especially of past forms; in order to deal with these even a 
trinomial system would in many cases be inadequate. He considered that sooner 
or later far more radical changes would have to be introduced. 
These remarks refer more especially to the higher classes of creatures, but they 
serve to show the danger of departing from the old course at present. It is not, 
therefore, because I consider the binomial system the most philosophic or the 
best, but because I consider it the least calculated to mislead under the circum- 
stances that it has been adopted for this Monograph. We must jog on as well as 
we can with the help of sub-genera and var. a and var. b, and this no doubt can 
be done without any difficulty. Moreover, in the case of fossil mollusca, we must 
never lose sight of the fact that, biologically, we are walking somewhat in the 
dark, and also that mineralisation, by the changes it sometimes superinduces, adds 
to our uncertainty in these matters. Hence the fossil-conchologist, treading on 
somewhat doubtful ground, should not be over anxious to emphasise differences 
the precise value and meaning of which are not so very obvious in all cases. 
When we have to deal with a demoid group, such as some of the small Cerithia 
for example, the larger the collection and the fewer the specific names we should 
be disposed to give, whereas the varietal names would be numerous. It is, in fact, 
these demoid forms with their numerous links which most require the assistance of 
a third name. Of course these remarks have reference to the Jurassic Gastero- 
poda only. The Cephalopoda might perhaps require somewhat different treat- 
ment; in fact, the difficulty as regards the Ammonites is practically got over by 
splitting the genus, and even that method is hardly enough for such a sporting 
group. 
