643 
withstanding highly useful, both as indicating changes of litholo- 
gical character, great lines of disruption and lower divisions of the 
same palzozoic group. In short, all researches up to this day have 
led to the belief, that the Lower Silurian fossils were the earliest 
created forms, and that this “protozoic” type prevailed during that 
vast succession of time which was occupied in the accumulation Of - 
all the older slaty rocks, until the Upper Silurian period, when new 
creatures were called into existence, and when the earlier forms 
diminished and were succeeded by a profusion of chambered shells 
which so abundantly characterize that epoch. 
This, Gentlemen, is I trust a good step gained. To establish upon 
sound data the true theory of organic succession in the oldest forms 
of life, is surely important, and we ought to rejoice that the Bri- 
tish islands have afforded us the means systematically to work out 
the question. Ascending then from these lowest types, the Upper 
Silurian zone is one of great distinctness in England, and in the 
Baltic—in the northern provinces of Russia and in North Ame- 
rica; the Wenlock, Dudley and Ludlow fossils having been abun- 
dantly found in both hemispheres. As soon, however, as we have 
advanced through this zone, a new era is announced by the pre- 
sence of the earliest Vertebrata. The minute and curious fishes im 
the uppermost bed of the Ludlow rock, are the earliest precursors 
of many singular ichthyolites which succeed in that enormous for- 
mation, termed from its mineral character in Scotland and parts of 
England, the Old Red Sandstone. But im this as in nearly every 
other deposit, lithological characters are fugitive, and the red, green 
and yellow sands of the North, are found even in our fclands) as 
in Devonshire and the adjacent tracts, to be replaced by black 
schists and limestones. But here again zoology enables us to in- 
terpret the language of nature, for it was merely by seeing the 
letters of the alphabet spread out before him in a cabinet, and 
without even having visited the country, that Mr. Lonsdale was 
led to conceive that a large portion of this tract, though very 
dissimilar in mineral aspect, would prove to be of the same age as 
the Old Red Sandstone. I need not tell you how the researches of 
Professor Sedgwick and myself, which first indicated the presence 
of some members of the carboniferous system of that tract, after- 
wards confirmed these views, nor need I remind you that we have 
since extended them to various parts of Germany and Belgium, 
for the abstracts are already in your Proceedings and the memoir 
is about to appear in your Transactions. 
I must here, however, acquaint you, that the paper by ourselves 
upon the Rhenish provinces is admirably illustrated by a description 
of the Devonian fossils of that region, prepared at our request by 
M. E.de Verneuil and M. d’Archiac, in which many new genera 
and species are established, and the group is delineated with close- 
ness. of research and profound knowledge of natural history. In the 
same communication these authors offer a general table of Palawo- © 
zoic fossils, which in sustaining in the strongest manner the true 
intermediate character of the Devonian system, as suggested by- 
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