Percoidea, or Perch-like Fishes 309 
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 
YS 
Fic. 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 
Sead? 
Fic. 242.—The Aspron, Aspro asper (Linneus). Rhone River. Family Percide. 
(After Seelye.) 
the sauger, but larger, characterized technically by having the 
ventral fins closer together. Another species, Cemtropomus 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 
