132 FACTS AND FANCIES 



SO fond of asserting that derivation is " demon- 

 strated " by geological facts : 



1. Species continued unchanged 28 per cent. 



2. Species migrated from abroad 7 '• 



3. Species continued with modiiication o " 



4. New species without known ancestors.... 65 " 



100 per cant. 



He shows that the same or very similar pro- 

 portions hold with respect to the cephalopods 

 and trilobites, and, in fact, that the proportion 

 of species in the successive Silurian faunae 

 which can be attributed to descent with mod- 

 ification is absolutely nil. He may well remark 

 that in the face of such facts the origin of 

 species is not explained by what he terms les 

 Hans poitiques de r imagination. 



The third part of Barrande's memoir, relat- 

 ing to the comparison of the Silurian brachio- 

 pods of Bohemia with those of other countries, 

 though of great scientific interest, and import- 

 ant in extending the conclusions of his previous 

 chapters, does not so nearly concern our pres- 

 ent 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 ascertaining if there is any basis in 



