194. MEMOIRS OF THE CARNEGIE MUSEUM. 
of G. carapo, the second species of the Gymnotine, as has already been intimated, 
may be the result of its color-markings and active, predaceous life. The other 
two subfamilies, the Sternopygine and Sternarchine, show a relatively high per- 
centage of injured individuals. This seems to be due to two causes: (1) the 
exposure of a large amount of tail to injury; (2) the survival of the injuries received 
in the region of the tail. 
The longer the caudal portion exposed the greater the chance of its being 
attacked and injured by other fishes. Size in itself, other things being equal, may 
be quite a factor in determining the liability to injury. This statement is borne 
out by an analysis of the injured specimens of Sternopygus macrurus. <A larger 
percentage of the large fishes have been injured than of the small ones. 
Sternopygus macrurus (Bloch and Schneider). 
Size. | Number of Specimens. Number Injured. Per Cent. Uninjured. 
155-250 mm. 50 7 | 14 
250-350 mm. 100 24 | 24 
350-500 mm. |e Soe mio) - eo = 3 Ree 60 
Potala sse-t.- | 155 | 34 
All the specimens mentioned in this table were taken at the same time in one 
catch from the Botanic Garden, Georgetown. Of course the element of time in 
addition to that of size enters into the comparisons in this table. The larger 
examples, being the older, have been exposed to injury for a longer period than the 
smaller. 
The long caudal portion, which contains no viscera or vital organs, may be 
mutilated without killing the fish. Specimens having been mutilated in this 
region are therefore in evidence. Species of a shorter type with the viscera occupy- 
ing relatively much more of the body, if injured, would be more liable to be fatally 
affected, consequently fewer mutilated specimens would be found in a large col- 
lection. The presence of so many mutilated specimens among the collections of 
Gymnotide does not necessarily mean that the Gymnotide are more frequently 
injured than other species of the same habit subjected to the same conditions, but 
it does show the injuries to be less frequently fatal. The frequent injury to the 
caudal portion seems due to the elongated tail. Since the Gymnotide survive 
these injuries because of the elongate tail and the extreme cephalad position of 
the viscera the question arises whether they are not “protectively shaped.” 
Regeneration is probably of little importance to the first two species, LE. 
electricus and G. carapo, as compared with its value to the Sternopygine and Stern- 
archine, for in these two subfamilies it tends to restore the protective shape. The 
power of regeneration seems about equally developed in both species subject to 
frequent injury and those not often injured. The same parts are regenerated by 
both groups and with about an equal degree of completeness. 
