2 BRITISH FRESH-WATER FISHES 



to the socket ; instead of following up the rich vein that he 

 had laid bare, they contented themselves with contemplation 

 of the precious metal he had extracted, and allowed the mine 

 to fill up with all kinds of rubbish. His admirers, far from 

 verifying and extending his observations, treated his con- 

 clusions as dogma, which, in accordance with the invariable 

 tendency of the human mind, became a nucleus for all that 

 was false, provided it was marvellous. 



Thus it came to pass that for eighteen hundred years the 

 science of ichthyology remained, not in the sound position in 

 which it was left by Aristotle, but encrusted with accumulated 

 error and falsehood. When the revival of learning reached 

 this department of science, its pioneers encountered a vast and 

 disheartening labour in clearing away these layers of ignorance. 

 Belon, Salviani, and Rondelet, working independently of each 

 other, published works on fishes in the sixteenth century, and, 

 among them, cleared the ground for the foundation of a system 

 of classification, whereon the Englishmen, Ray and Willughby, 

 commenced to build in the seventeenth century ; then followed 

 Peter Artedi, the fellow-student of Linnaeus, who practically 

 completed the edifice of orders, genera, and species in which 

 ichthyologists conduct their study at this day. Alterations 

 have been made since then by many distinguished men of 

 science ; but these have been but modifications and extensions 

 of the original plan. Arbitrary statement, a priori assumption, 

 and venerable fable have been consigned for ever to the rubbish- 

 heap ; henceforth the only furniture admitted to the edifice is 

 sound fact and rational induction. 



I have thought it expedient to make these observations 

 before explaining the object of the present work. Of the 

 vast variety of fishes now accurately known to science, only 

 six-and-twenty genera and less than twice that number of 

 species can be reckoned as inhabiting British fresh waters. In 

 describing these, it may seem to some that the general reader 

 might have been spared the unpopular terminology of scientific 



