Percoidea, or Perch-like Fishes 



39 



disturbed, every fin perfect, tail clean-cut, and his great, big 

 wall-eyes stand out with that life-like glare so characteristic of 

 the fish." 



Similar to the wall-eye, but much smaller and more trans- 

 lucent in color, is the sauger, or sand-pike, of the Great Lakes and 



FIG. 241. Sauger, Stizostedion canadense (Smith). Ecorse, Mich 



Northern rivers, Stizostedion canadense. This fish rarely exceeds 

 fifteen inches in length, and as a food-fish it is of correspond- 

 ingly less importance. 



The pike-perch, or zander, of central Europe, Centropomus 

 (or Sandrus} lucioperca, is an excellent game-fish, similar to 



Fia. 242. The Aspron, Aspro asper (Linnaeus). Rhone River. 



(After Seelye.) 



Family Percidce. 



the sauger, but larger, characterized technically by having the 

 ventral fins closer together. Another species, Centropomus vol- 

 gensis, in Russia, looks more like a perch than the other species 

 do. Sandroserrus, a fossil pike-perch, occurs in the Pliocene. 

 Another European fish related to the perch is the river ruff, 

 or pope, Acerina cernua, which is a small fish with the 

 form of a perch and with conspicuous mucous cavities in 

 the skull. It is common throughout the north of Europe 



