180 



MEMOIRS OF THE CARNEGIE MUSEUM. 



jured anal. The entire piece was normally scaled and marked with the typical 

 bands of pale yellow and dark blue (compare with Fig. 22, the normal tail). It 

 differed chiefly in being a little smaller than the uninjured jmrt of the body, which 

 gave the fish a constricted appearance along the line of injury. 



Fig. 20. Regenerated Tail. Gymnotus carapo (Linnaeus), Santarem, Brazil. 



The third case was quite different. This fish, a specimen one hundred and 

 thirty millimeters long, from Aqua Quente, Paraguay, had received an injury 

 parallel to the lateral line. The caudal appendage and caudal portion of the 

 body were split for a distance of thirty-five millimeters. Both pieces had rounded 

 themselves out so that there were two well-formed caudal appendages, each longer 

 than the normal. The ventral tail has an anal fin regularly attached except for a 

 slight fold (see Fig. 21). 



Fig. 21. Split Tail. Gymnolus carapo (Linnaeus), Aqua Quente, Paraguay. 



Fig. 22. Normal Tail. Gymnotus carapo (Linna;us), Holniia, Briti.sh Guiana. 



Taken collectively these regenerations show G. carapo capable of rather 

 complete regeneration of injuries in the caudal region. Caudal api)endage, muscle 

 scales, color markings, and anal fin were all restored. It, of course, could not be 

 determined absolutely whether these injuries had been received when the fishes 

 were much smaller and the regenerated parts, after some fraction of the part re- 

 moved had been restored, had grown with the rest of the fish, or whether the regen- 

 erations were the results of recent injuries, and really rei)resent the amount of tissue 

 lost. The appearances all favor the view that the injuries were recent. The 



