SALMON. 85 



extremely numerous in species in the Old and New Worlds, of 

 which the following are well known in England : — The Roach 

 [L. rutilus), the Chub (L. cephalus), the Dace (L. leuciscus), the 



Fier. 72. 



m 



Mahaseer {JBarbus mosal). 



Rudd (L. erythrophthalmus), and the Minnow (L. phoxinus). 

 Other British Cyprinoids are the Tench [Tinea tinea), the Bleak 

 [Alburnus alburnus), the Breams (Abramis brama and blicca), and 

 the Loaches [Nemachilus barbatulus and Cobitis taenia). 



The Haplochitonida are a small but interesting family, inasmuch 

 as they represent the Salmonoids in the temperate parts of the 

 Southern Hemisphere. They differ from the latter family in the 

 structure of the jaws,and by the total absence of pyloric appendages; 

 but they possess an adipose fin like the Salmonoids. Two genera 

 are known: one, Haplochiton, is abundant in the lakes and streams 

 of the Falkland Islands, Patagonia, and Chili ; these fishes have 

 the general appearance of a Trout, but are naked. The second 

 genus, Prototroctes, is scaly, and resembles a Vendace (Coregonus) ; 

 the settlers of South Australia and New Zealand call them Grayling. 



The Salmonidce (Case 21) are one of the most valuable families [Case 21.] 

 of the Class of Fishes. They are inhabitants of the sea and fresh 

 water ; but the majority of the marine genera are deep-sea forms. 

 The freshwater forms are peculiar to the Temperate and Arctic 

 zones of the Northern Hemisphere, one only (a Smelt) occurring 

 in New Zealand. Many migrate periodically or occasionally from 

 fresh water to the sea, or vice versa. The genus Salmo, containing 

 the Salmon, Trout, and Char, is abundant in species, some being 



