THE GYMNOTID EELS OF TROPICAL AMERICA. 193 
end of the caudal appendage thirty-seven millimeters had been completely restored 
as far as could be determined; (2) an irregular, semicircular piece fifty-seven milli- 
meters long and twenty-two millimeters deep had been removed from the anal 
fin and anal muscles quite well caudad on the anal fin. Here a strip twelve milli- 
meters wide, bearing a narrow fringe of fin fused at both ends with the old anal, had 
been regenerated; (3) a piece twenty millimeters long and thirty millimeters deep 
was gone from the anal region about one hundred millimeters back of the head. 
In its place was a regenerated mass twenty-two millimeters wide with a rather 
complete fin on its ventral edge, this fin being fused with the old anal on both ends. 
This fish showed no abnormalities to account for being thus mutilated. It an- 
swered in every particular the specific measurements of the species. Plate X XI, 
fig. 4 gives an outline drawing of this fish showing the regenerations first mentioned. 
Source of Injury.—The source of these injuries was supposed to be predaceous 
fishes. As many small alligators and snakes are found in the same habitat these 
may be responsible for part of them. The wounding of one Gymnotid was ob- 
served. A specimen of the ‘“‘hooree,”’ Hoplias malabaricus, was seen to bite off the 
caudal portion of an Higenmannia virescens. It had been placed in a small trench 
with several of the latter. The hoorees are abundant in all of the streams from 
which either Higenmannia or Sternopygus were collected in British Guiana. 
General Discussion. 
The power of regeneration in the Gymnotide, as long as the injury is not fatal, 
is quite general. All of the species of which more than a very few specimens were 
examined showed some regenerated parts. As long as the mutilated specimens 
amount to no large fraction of the whole number, they may be considered as 
chance injuries. Out of a large number of individuals of any species of animal 
some may be expected to have been injured in the natural course of events On 
the other hand, when the number of injured in the collection of a given species 
amounts to a considerable per cent, some other factor than chance alone has 
probably been operative. Tabulating the total number examined in each sub- 
family with the number injured, we have: 
Subfamily. Number of Species. | Specimens Examined. | Specimens Injured. | Per Cent. Injured. 
1. Gymnotine....... 2 | 250 | u 3 
2. Sternopygine..... 10 : 939 | 115 12 
3. Sternarchine.....-| plo 113 20 eo tee We eee Oba 270s 
INDE S 66 Ga GAGDE 27 1302 — el 
This table and all of the special data show the members of the first subfamily 
to be subject to only chance injury, and those of the other two, to frequent injury. 
The immunity from frequent injury of FZ. electricus, one of the species of the first 
subfamily, is undoubtedly due to its remarkable electric power. The immunity 
