Percoidea, or Perch-like Fishes 



3*3 



nigrum, the Johnny darter in the West, and Boleosoma olmstedi 

 in the East are among the commonest species, found half hid- 

 den in the weeds of small brooks, and showing no bright colors, 

 although the male in the spring has the head, and often the 

 whole body, jet black. 



Crystallaria asprella, a large species almost transparent, 

 is occasionally taken in swift currents along the limestone 



FIG. 248. Crystal Darter, Crystallaria asprella (Jordan). Wabash River. 



banks of the Mississippi. Still more transparent is the small 

 sand-darter, Ammocrypta pellucida, which lives in the clearest 

 of waters, concealing itself by plunging into the sand. Its 

 scales are scantily developed, as befits a fish that chooses this 





FIG. 249. Sand-darter, Ammocrypta clara (Jordan & Meek). Des Moines River. 



method of protection, and in the related Ammocrypta beani of 

 the streams of the Louisiana pine-woods, the body is almost 

 naked, as also in loa vitrea, the glassy darter of the pine-woods 

 of North Carolina. 



In the other darters the body is more compressed, the move- 

 ments less active, the coloration even more brilliant in the 

 males, which are far more showy than their dull olivaceous 

 mates. 



To Etheostoma nearly half of the species belong, and -they 



