Tlie Sco])e of Paleont(il(i<iii. — Will! am k. 151 
Aud the order. (1) Silurian system, (2) Old Red system, (3) 
Carboniferous system, it was believed, expressed a continuous 
stratigraphical series. When certain fossils from the limestones 
of Newton, Bushel, and other localities in South Devonshire 
were given Lonsdale to descril)e, he determined them to be of the 
age of the Old Red sandstone, in the following way, (to use his 
own language): "It was therefore by combining together this evi- 
dence, the presence, in the same series of beds, of shells resem- 
bling or identical with Mountain limestone species, of Silurian 
corals, the CaJceoht Sandal iiui^ and various distinct Testacoa, that 
1 was induced to suggest that the South Devon limestones are of 
an intermediate age between the Carboniferous and Silurian sys- 
tems, and consequently of the age of the Old Red sandstone:" 
(Notes on the age of the Limestones of South Devonshire by 
William Lonsdale, F. G. S. [read March 25, 1840] Trans. Geol. 
Soc. 2d Sec, Vol. v.. p. 72L) 
Sedgwick and Murchison adopted Lonsdale's conclusions without 
reserve, although they produced radical change in the classification 
they had already pul)lished, and on the strength of them they 
founded the Devonian System, and said: "This is undoubtedly 
the greatest change which has ever been attempted at one time in 
the classification of British rocks,' and further, '-So far from, 
thinking ourselves rash and hasty in drawing the preceding con- 
clusions, we think we may rather be accused of being over-cau- 
tious and tardy in accepting evidence, however opposed to 
commonly received oi)inions."" 
(Sedgwick and Murchison, "(Jn the Physical Structure of 
Devonshire, etc., Pt. ii, on the Classification of the Older Strati- 
fied Rocks of Devonshire and Cornwall," Trans. Geol. Soc, 2d 
Sec, Vol. V, p. 688.) 
This interpretation was not stratigraphical, nor was it a case of cor- 
relation by means of a common species of fossils, after the William 
Smith method of paleontology, but it was a case of determining 
the stratigraphical position of the Devonian fauna by a comparison 
of its species with those of other faunas from which it ditt'ered. It 
is a typical case of what 1 would call Comparative Paleontology. 
In l)0th of the cases cited it will l)e noted that the fundamental 
fact underlying the determinations made, consists in the I'ecog- 
nized natural order of setpience of species corresponding to the 
stratigraphic order of the rocks containing them. 
