British Fresh-Water Fishes 



INTRODUCTION 



There are few features of human history more startling and 

 unaccountable than that intellectual frost which arrested the 

 growth of natural science at a point of precocious and pros- 

 perous development. In the fourth century before Christ, 

 Aristotle laid the foundations of a sound system of zoology, 

 based on original research and observation ; a system which 

 only required correction and expansion by the co-operative 

 labours of succeeding generations of students to embrace all 

 living creatures in their right relation to each other. In regard 

 to aquatic animals, especially, Aristotle had a very keen discern- 

 ment, surprising in a student who, so far as is known to us, 

 enjoyed no mechanical aid to vision. He neither confused 

 cetacean mammals — whales, dolphins, and the like — with fishes, 

 nor eels with serpents, but defined branchia and fins as the 

 distinctive organs of true fishes. Aristotle erred in some 

 directions, indeed, and came far short of full knowledge in 

 others, as every student is liable to err and bound to come 

 short ; but we are filled with wonder, not at his limitations, 

 but at the scope of his knowledge and the general rectitude of 

 his conclusions. 



Yet when Aristotle died, natural science stood still. Men, 

 indeed, acknowledged his work as a revelation ; but instead of 

 passing the torch from hand to hand, they suffered it to burn 



I 



