38o A HISTORY OF FISHES 



families of oceanic Ceratioids, all differing from their Perch-like 

 ancestors in having the first ray of the dorsal fin placed on the 

 head and modified into a line and bait. Finally, there are the 

 fresh-water Spiny Eels {Opisthomi)^ a small order containing 

 fishes probably allied to the Percomorphi; and the eel-like 

 Symbranchii, which may be descended from some Blennioid 

 stock. 



