THE GYMNOTID EELS OF TROPICAL AMERICA. 



187 



may change through orange, purple, and green. In general they are red or orange- 

 red, with a golden green cast dorsally. The yellow pigment dissolves in alcohol 

 and the entire fish becomes opaque. Alcoholic specimens of Eigenmannia are 

 straw-yellow, and of Sternopygus stone-grey (because of the greater number of blue 

 chromatophores). Figures 29-32 give outline drawings of G. Carapo, S. macrurus, 

 E. virescens, and H. brevirostris, showing the location of the viscera. 



From these figures it may be seen that the viscera proper occupy about the 

 same space in all of three species, but the air-bladder of S. macrurus is much longer, 

 being conical in shape and extending some distance beyond the rest of the viscera. 



For the interpretation of the data, the fish may be divided into three regions: 



Fig. 30. Air Bladder of Sternopygus macrurus (Bloch and Schneider.) Side-view. 



(1) all behind the middle which may be termed the "caudal half"; (2) that portion 

 of the body in front of this line and above the lateral fine which may be designated 

 as the "dorsal quarter"; (3) that portion below the lateral line and in front of 

 the caudal half which may be called the "ventral quarter." The detailed data of 

 the eleven special collections of these three species is given in the following table. 



1 



2 

 3 

 4 



)S. macrurus . 

 S. macrurus. 

 S. macrurus. 

 S. macrurus. 



Georgetown. . . 

 Georgetown . . . 



Wismar 



Hububa Creek . 



155-500 mm. 

 200-400 mm. 

 118-212 mm. 

 190-300 mm. 



Total. 



The number of individuals iow^d regenerating injuries of some sort is sufficient 



