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 Linneus, 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, @ 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 
