liv INTRODUCTION. 
two other species) had been placed in our old Museum, as Builth and Llandeilo fossils. 
More than forty years since, two or three species from Meifod had been placed in our old 
Museum (by my predecessor in the Woodwardian chair), side by side with one or two 
species from Snowdon, and identified (I believe correctly) though not named. A very fine 
collection had been made by Mr Hennah from the Plymouth fossils. Some of the species 
were named (when I first saw them in 1819), and not long afterwards several Plymouth 
species were figured*. Many Scandinavian fossils had been well described and figured. 
Some characteristic specimens from Scandinavia, and some good specimens of the long- 
winged Spirifers, and other fossils from the Rhenish provinces, had been placed in the old 
Woodwardian Cabinets by the founder of our Museum. 
We knew in 1822 as certainly as we know now, that Trilobites, Orthoceratites, and 
multitudinous species of Brachiopoda, formed a very characteristic portion of the oldest 
Paleozoic fauna. But no information of this kind could lend us the least help in the 
classification and nomenclature of the lower division of the Paleozoic Series, till the fossils 
had not only been more perfectly collected and described, but also referred to their right 
place, in some natural succession of physical groups established on good sectional evidence. 
I had, indeed, ascertained before 1824, that there were two distinct groups of fossils 
in the Cumbrian mountains: viz. the Coniston group with its numerous Brachiopods, Tri- 
lobites, and Orthoceratites; and the much higher group of Kendal and Kirkby Moor with 
its numerous unsymmetrical bivalves, (Lamellibranchiata) and other fossils. Very few of the 
species had been at that time correctly named: but when the fossils were put side by side, the 
two groups did not appear to contain so much as one species in common. I had done well 
(if my own reputation had been my only object) had I collected more largely (certainly 
no hard task) the fossils of the Coniston and the Kendal group, had I submitted them to 
Mr Sowerby for their specific determination, and then left the event to fortune. But I could 
not bear to deal in that manner with a great question in Palzozoic Geology; while, for 
three reasons, its difficulties were unsolved.—(1) Because no fossils had been found in 
the vast group of slates and porphyries below the Coniston limestone. (2) Because there 
was a great, and unknown, chasm between the Kendal group and all the overlying rocks, 
whether Devonian or Carboniferous. (3) Because the Plymouth fossils (and that was 
after all the great difficulty), spite of their approach to a known Carboniferous type, were in 
a group which nearly all English Geologists, of that day, considered of a much older date 
than the coarse greywacké of Kirkby Moor. I consequently left the Cumbrian mountains in 
1824—after laying down the demarcation of the physical groups, step by step, from actual 
survey, and determining their order in the natural sections—not without a feeling of 
bitter disappointment. In a subsequent year I sought in Scotland, but in vain, for some 
* In 1819 I traced the Plymouth group into Cornwall, and found it overlaid by old-looking chloritic slates. I there- 
fore concluded that (spite of the newer Palzozoic type of its fossils) the Plymouth limestone must belong to a very old 
Paleozoic group! To have denied this conclusion would (at that period of our knowledge) have been regarded as an 
absurdity not less than denying the truth of the first book of Euclid. Mr Hennah and Mr Greenough were at that time, 
if I mistake not, disposed to identify the Plymouth with the Carboniferous limestone. 
