CLASS PISCES: ORDER TBLE08TBI. 

 Mg. SSe. 



191 



LopW/us americarius. Fishing Frog. iV- 



to move in every direction ; the other two turning only back- 

 ward and forward. The sluggish creature lies in the mud at 

 the bottom of the water, and, waving the first spine, attracts 

 the curious fishes with this glistening bait; but, as they nib- 

 ble, the rear spines knock them into its capacious mouth. 



P e r c i d ae (dusky). — Perch are 

 found both in salt and fresh water. 

 Their operculum is so constructed 

 that they can be kept alive in the air 

 for hours by occasionally pouring 

 water upon their gills. 



Xiphiidse (sword-like). — The 

 Sword-fish is remarkable for its upper jaw being prolonged 

 into a formidable weapon. As its food consists only of squid 

 and small fishes, the use of the "sword" is a mystery.* 



Fig. 323. 



Yellow Perch, 



33,pMa8 gla^m, Sword-flsh. 



* Some species have a sword so strong that it has frequently been driven through 

 the coppered hull of a vessel, a third of its length being sawed off on the inside. 



8 



