THE ANTIQUITY OF MAN AND THE ORIGIN OF SPECIES. 599 
do they survive it. This and the previous results, as well asthe fact that parallel 
changes go on in groups having no direct reaction on each other, prove that 
variation is not a progressive influence, and that specific distinctions are not 
dependent on it, but on the ‘‘sovereign action of one and the same creative 
cause,” as Barrande expresses it. These conclusions, it may be observed, are not 
arrived at by that slap-dash method of mere assertion so often followed on the 
other side of these questions, but by the most severe and painstaking induction, 
and with careful elaboration of a few apparent exceptions and doubtful cases. 
His second heading relates to the distribution in time of the genera and 
species of brachiopods. This he illustrates with a series of elaborate tables, 
accompanied by explanation. He then proceeds to consider the animal popula- 
tion of each formation, in so far as brachiopods, cephalopods and trilobites are 
concerned, with reference to the following questions: (1) How many species are 
continued from the previous formation unchanged? (2) How many may be 
regarded as modifications of previous species? (3) How many are migrants from 
other regions where they have been known to exist previously? (4) How many 
are absolutely new species? ‘These questions are applied to each of fourteen 
successive formations included in the Silurian of Bohemia. The total number of 
species of brachiopods in these formations is 640, giving an average of 45.71 to 
each, and the results of accurate study of each species in its characters, its varie- 
ties, its geographical and geological range, are expressed in the following short 
statement, which should somewhat astonish those gentlemen who are so fond of 
asserting that derivation is ‘‘ demonstrated” by geological facts: 
IO pecies Continued whemameed) =) 40). 21 '28) per cent: 
24 Species migrated iromabroad). 2 15.77 ss 
3. Species continued with modification. o ‘“ 
4. New species without known ancestors. 65 us 
100 per cent. 
He shows that the same or very similar proportions hold with respect to the 
cephalopods and trilobites, and in fact that the proportion of species in the suc- 
cessive Silurian faunze, which can be attributed to descent with modification, is 
absolutely z/. He may well remark that in the face of such facts the origin of 
species is not explained by what he terms ‘‘les élans poétiques de limagination.” 
The third part of Barrande’s memoir, relating to the comparison of the 
Silurian brachiopods of Bohemia with those of other countries, though of great 
scientific interest and important in extending the conclusions of his previous 
chapters, does not concern so nearly our present subject. 
I have thought it well to direct attention to these memoirs of Barrande, 
because they form a specimen of conscientious work, with the view of ascer- 
taining if there is any basis in nature for the doctrine of spontaneous evolution of 
species, and, I am sorry to say, form a striking contrast to the mixture of fact and 
fancy on this subject which too often passes current for science in England, 
