THE FRESHWATER FISHES 

 OF THE BRITISH ISLES 



CHAPTER I 

 THE LAMPREYS 



Lampreys and Hag-fishes. The Lamprey family : the Sea 

 Lamprey specific characters size distribution breeding 

 death follows breeding structure and habits of larvae 

 metamorphosis habits of adult origin of name value as 

 food. The Lampern : differences from Sea Lamprey distribu- 

 tion migrations breeding food and habits uses other 

 names. Planer's Lamprey : differences from Lampern 

 distribution metamorphosis 



THE Lampreys (Petromyzonidce) and Hag-fishes 

 (Myxinidce] differ widely in structure from 

 the Selachians and true fishes, and in many respects 

 are more generalized ; they constitute a distinct class, 

 the Cyclostomata or Marsipobranchii. They are 

 naked eel-shaped animals without paired fins, and 

 with the median fins supported by internal carti- 

 laginous radials, but lacking dermal fin-rays; the 

 internal skeleton is cartilaginous, and there are no 

 bones anywhere ; the terminal mouth has no jaws, but 

 there is a very muscular protrusible tongue, which 

 is armed with cuspidate horny laminae, and works 

 i 



