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. MACTrUrUs, 
E, virescens, and H. brevirostris, showing the location of the viscera. 
From these figures it may be seen that the viscera proper oceupy 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: 
Fic. 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 line 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. 
| | | are 
| Num- | Num- Per eas ze 
Col. | Species | Locality Length ber of | ts eee Mors: 1 Ven- 
ND: | a = i Speci: | sener- | gener- \Caudal Quar | tral 
| | mens. | ations. ations.| Half. ter, | Quar- 
ter. 
1 | #. virescens....... Georgetown....... | 105-800mm. | 155 | 24 | 15 | 18 OFF AG 
2 | #. virescens.......| Georgetown....... 100-300 mm. = 50. 10 20) 8 0 4 
Or Bie PUTeSCENS 5.0.41. - | Georgetown....... | 160-320 mm. Sts) AG |) ay | et ON ez 
4 | E. virescens....... WatnWes | Gogdacuce 150-290 mm. 30 5 16 5 Oy 
| ee ee ene foneesic cel OZR Ck re eee ROS ase 
NEE | PE TROCTODS svete | Rockstone......... 165-200 mm. 32 4 | 12 4 0 0 
2 Tumatumari....... 165-180 mm. 12 2 WG 1 0 1 
3 (Crab) Hallsis 22... | 125-150 mm. 12 1 | 8 1 0 0 
i ee eee foal lea Gao A 
1 | S.macrurus...... | Georgetown.......| 155-500 mm. 104 2S leas 6 0 | 2 
2 |S. macrurus...... | Georgetown....... 200-400 mm. 18 3 17 3 0 1 
&. |USS WAVES 5 socal MARIS Goouodcouc 118-212 mm. | 10 2 | 20 2 | @ 
4 |S. macrurus...... | Hububa Creek ..... 190-300 mm. 17 3 17 3 0 2 
Br es, rtm eee 149 | 16 | 10 | 14 | 0 5 
The number of individuals found regenerating injuries of some sort is sufficient 
