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actinazoon^ not an annuloida, nor an annulosa, but a mollusc. 
It is one of the most ancient shells^ and is known by the 
name of the Obolella/^ It belongs to a group well known 
to the zoologist as the Brachiopoda, and which holds a 
position in the scale of organization only a little lower than 
the oysters and mussels of the present day. 
Now every student of zoology knows that there is a wide 
chasm between the protozoa, or hydrozoa, and the mollusca. 
If, therefore, the Obolella were developed out of an 
Oldhamia, there must have been many intermediate links. 
For, according to the hypothesis, natural selection ‘‘ can 
never take a sudden leap, but must advance by short and 
sure, though slow, steps. Is it not very strange and un- 
fortunate that none of these sure steps are to be found ? 
Continuing our journey upwards in the series of rocks, and, 
therefore, onwards in the course of time, what do we find ? 
Not a more highly- developed mollusc, but multitudes of 
trilobites,^^ creatures allied to the decapod crustaceans of 
the present day. True, there are found associated with these 
creatures fossil sponges and encrinites; but the former belong 
to the protozoa, and ought, on the hypothesis of evolution, 
to have been found in the upper portion of the Lauren tian, 
or in the Hurion, while the latter rank with the echino- 
dermata, and ought to have been found much lower down in 
the series of rocks. 
Entering the great Silurian system, most important negative 
evidence is obtained. In these rocks are found, for the first 
time, immense numbers of fossil corals, creatures belonging 
to the actinazoa, and, side by side with these lowly creatures, 
the evidence of a rapid growth of molluscan life. Here are 
found the shells which were embedded in the soft tissues of 
a kind of cuttle-fish, and what mighty cuttle-fish they must 
have been when their internal shells are found to measure 
seven or eight feet in length ! 
Let us linger for a minute to contemplate the exact nature 
of these cuttle-fish. First, then, we remark, that they occupy 
the highest position in the scale of molluscan life ; second, 
they approach very nearly in some part of their organization 
to the vertebrate section of the Animal Kingdom. In these 
molluscs there is a brain enclosed in a cartilaginous brain- 
case, and, what is still more important in this discussion, the 
cuttle-fish has special ganglia for the sole purpose of origin 
to the nerves of sight. How strange that these highly-formed 
molluscs should come next to the Crustacea. Where is the 
evidence of the evolution of the one out of the other ? 
Passing now to the upper portion of the Silurian series, we 
