Bibliographical Notice. 489 
About 21 per cent. of the genera are common to the two hemi- 
spheres. 
Many philosophic deductions are drawn by Dr. Bigsby from the 
results of his long-continued study. He notes the fewness of 
species, whether Devonian or Carboniferous, common to the two 
Hemispheres—in accordance, he observes, with the more or less 
distinct areas of deposits, possibly, in some degree, homotaxeous 
rather than contemporaneous. He finds, as is usually the case, 
that the species of the lowest organic rank are the most frequently 
found in widely separate countries, as Plante (1 in 15), Amorphozoa 
(1 in 8 or 10), Foraminifera (1 in 7); while the higher orders, 
Reptilia, Pisces, Insecta, Crinoidea, Mollusca, &c., rarely remove 
from their native regions, east or west. Numerous suggestive 
statements as to the conditions and extent of stratal groups, 
constant or non-constant, the mutual relations of species, their 
occurrence, distribution, persistency, migration, recurrence, and 
their natural-history standing, are given in the Introduction, 
pp. V—-x. 
In contemplating this single portion, one trace, as it were, of an 
exhaustless treasury of proof upon proof of Omnipotent Design, the 
author agrees with Hunter and Owen that “ the creative force has 
not deserted the earth during any of the epochs of geological time 
that have succeeded to the first manifestation of such force, and 
that in respect to no one class of animals has the operation of that 
force been limited to one geological epoch. Perhaps the most im- 
portant result of paleontological research has been the establish- 
ment of the axiom of the continuous operation of the ordained in- 
coming of new species of living things” (‘Hunter’s Essays and 
Observations,’ arranged by R. Owen, F.R.S.). 
The ever-active influence of the great Presiding Mind thus consum- 
mates the Creator’s great Design through the Past and the Future, 
which is to Him To-day ; and, adds the author, ‘‘ so vast and ever 
active is the power of conditions (that is, of the many surrounding 
agencies, of long periods of time, and of original impress from with- 
out), that I am well satisfied to expect from them the organic 
changes we observe, and without seeking further,” 
A well-founded hope is expressed in the Introduction that “ this 
work will assist in opening out a new field of inquiry into what 
may be called ‘Comparative Paleontology’”—that is, comparison of 
the life and conditions of geological horizons, far apart in succession, 
whether of wide extent or divided among limited areas. 
These labours of Dr. Bigsby among the Silurian, Devonian, and 
Carboniferous Fossils certainly widen most extensively that field 
of research already commenced by Bronn (in his ‘ Lethwa Geognos- 
tica’) and others, and enable the several students of different groups 
of fossils and their strata both to begin and to proceed with their 
work far more satisfactorily, and with far less liability to error, 
than heretofore. All that has been done in these several paleonto- 
logical walks is elaborately catalogued and clearly expressed by our 
author ; and the mistakes of naturalists, word-makers, copyists, and 
Ann. & Mag. N. Hist. Ser. 5. Vol. i. 33 
