266 FISHES 



Danube ; in Asia are found Macrones and Pseudobagrus which 

 are more common in India, while in China occurs one species of 

 the North American genus Amiurus. The Esocidae or pike 

 family are characteristic of the region we are considering, al- 

 though there are only two species, the pike and a small fish 

 called Umbra crameri, living in stagnant waters in Austria and 

 Hungary. Of Percidae there are several species, the common 

 perch, widely distributed, the pope, Acerina cernua, the large 

 pike-perches, Lucioperca, of Eastern Europe and Asia, and 

 several others such as Percarina in Southern Russia and Aspro 

 in the Rhone and Danube. Cottus gobio, the millers thumb, 

 and one or two other species of Cottus, and Lota vulgaris, the 

 burbot, are also characteristic. 



The fresh-water fish-fauna of a continent being determined 

 partly by climate and partly by means of communication, it is 

 not surprising to find that the fresh-water fishes of North 

 America are more similar to those of the Europo-Asiatic region 

 than to those of South America, the connection with the latter 

 being geologically recent. The similarities are shown by the 

 sturgeons, the salmonoids, the carps, the pikes and the perches, 

 though among these there are of course minor differences. The 

 European trout is absent, but there are numerous similar species 

 west of the Mississippi, while to the east are species of Salveliuus 

 or char. That the sturgeons and migratory salmonoids of the 

 North Atlantic and North Pacific should ascend rivers of the 

 east and west of North America as in Europe and Asia requires 

 no explanation. These are not exclusively fluviatile fishes. 

 Species of the carp family are as abundant in North America 

 as in Europe, but the species and genera are mostly differ- 

 ent ; in the west Leuciscus, the commonest European genus, 

 occurs, and also Abramis, the bream genus. The common pike 

 occurs and another larger species as well as three smaller; there 

 is also a species of Umbra. Perches are numerous but for the 

 most part different from those of Europe, the common perch being 

 represented by the yellow perch, Perca flavescens, while the 

 other species are small and belong to genera unknown in Europe 

 or Asia. On the other hand, there are important differences 

 between the two regions. The Holostean Ganoids, three species 

 of bony pike (Lcpi'dosteus)and one of bow-fin (Arnm), are peculiar 

 to N. America. Of the carp family loaches are wanting and the 



