HUGHES : ADAM SEDGWICK. 
265 
seemed to avoid questions of nomenclature, but we have no difficulty 
in making out what the rocks were that he referred to under the 
head of Middle Division of the Cambrian Slates, as he g-ives a good 
list of fossils which shows them to be the well-known Bala Beds of 
our modern terminology. In November of the same year, he wrote 
a fuller paper on the Palaeozoic (Protozoic) Rocks of N. Wales, in 
which he gives some further sub-divisions, and fuller descriptions of 
sections across the country. 
There is some difficulty in following the palseontological evi- 
dence in the absence of figures, as more knowledge has called for 
closer discrimination in the species and genera, and many names 
have been changed since those days, as may be seen by reference, 
for instance, to the Silurian system, where the excellent figures 
enable one to determine at once what species was intended. There- 
fore, it is probable that when, for example, we read of Asaphus 
(Ogygia) Buchii being found about the horizon of the Arenig rocks, 
it was probably Ogygia scutatrix or peltata, and so on for man3' 
others. However, we have here a clear sequence given in the 
Cambriam Rocks. The Arenig slaty beds overlaid by the porphy- 
ritic series, and this by various divisions clearly belonging to the 
Bala Beds. 
We see clearly enough what he meant by Cambrian, viz., every 
rock that could be made out to follow in conformable succession 
below the Sandstones at the base of the Denbigh Flags. He left 
somewhat doubtful many of the metamorphic rocks of Anglesea and 
Carnarvonshire. He had not yet clearly correlated the rocks of N. 
Wales with those of the Lake District, and he felt that as he pro- 
ceeded south there was much difficulty in making his sections agree 
with those of Murchison, but his series was clear, as shown in the 
vertical section. 
In the latter part of this paper (will it be believed ?) the nomen- 
clature, used by Sedgwick was altered in the proof-sheets by 
Warburton, in order to bring it into accord with the now more 
favoured terminology of Murchison. Altered without Sedgwick's 
consent. This statement has been made over and over again and 
never contradicted. 
