FRESHWATER FISHES. 57 



houting (Coregonus oxyrhynchus, Linn.), belonging to the Sal- 

 monidae, and the sea-Jamprey exist in the vine-region of the 

 Rhine, but are wanting in that of the Danube ; while the latter 

 possesses here and there the zingel (Aspro zingel), the streber 

 (Aspro vulgaris), and several species of sturgeon, which are 

 wanting in the Rhine. 



It is not possible, at present, to ascertain the Miocene river- 

 regions of Switzerland. In many places a few remains (chiefly 

 scales and ribs) have been found ; but (Eningen alone has fur- 

 nished numerous specimens capable of determination. These 

 are frequently still furnished with their scaly covering, and are 

 sometimes wonderfully well preserved. They occur both in the 

 upper and the lower quarry of (Eningen, but are restricted to 

 particular beds. Up to the present time thirty-two species have 

 been described*, belonging to fifteen genera. Of these genera 

 only one, allied to the Carps, but distinguished by its rounded 

 caudal fin (Cyclurus), is extinct; all the others are still met with 

 living in fresh waters. The fish-fauna of (Eningen therefore 

 differs entirely from that of Matt. Not only are the fishes of 

 Matt of marine origin, whilst those of (Eningen belong to fresh 

 water, but the (Eningen fishes approximate more closely to those 

 now living. While only half of the Eocene fishes of Matt be- 

 long to genera of the present, |1 of the (Eningian species can 

 be referred to existing genera. 



Of the fifteen genera at (Eningen, twelve (with twenty-five 

 species) are still to be found in the fresh waters of Switzerland. 

 In the Miocene age a great pike was the king of freshwater 

 fishes, large-scaled roaches (Leucisci), like L. argenteus and L. 

 nasus, and perches sported in the tranquil Lake of (Eningen ; 

 loaches and tenches in great numbers buried themselves in the 

 mud, and bull-heads (Cottus) and eels were not wanting. 

 Several of these species are very nearly allied to existing Swiss 

 species (such as the pike, and some of the loaches, andZ/ewmci), 

 whilst others are related to species of distant countries. Thus 

 the Miocene perch (Perca lepidota, Ag.) differs considerably 

 from the common Swiss perch, and most nearly resembles, ac- 

 cording to Agassiz, the species of India and New Zealand. It 



* See Agassiz, ' Recherches sur les Poissons fossiles,' v. p. 78 ; and Wink- 

 ler, ' Description des Poissons fossiles d'CEningen ' (Harlem, 1861). 



