186 MEMOIRS OF THE CARNEGIE MUSEUM. 
No specimens of Sternarchella balenops (Cope), Sternarchogiton nattereri 
(Steindachner) and Orthosternarchus tamandua (Boulenger) were examined, and 
no recorded regeneration for the first two species was found. However in his 
original description of O. tamandua, Boulenger speaks of his unique type as having 
a regenerated caudal confluent with the anal and figures it thus (op. cit., 1898, 
p. 427, pl. XLII). A second specimen of this same species, recorded and figured 
by von Ihering (op. cit., 1907, p. 277, pl. VIII, fig. 1), had the same type of a regen- 
erated caudal. 
In conclusion, eight of the fifteen species of Sternarchine are known to possess 
the ability to regenerate muscle, fin, rays, and scales. Several of these species 
regenerate new caudal fins from various levels more cephalad than that at which 
the caudal fin normally occurs, entirely without, or with only a very small caudal 
peduncle. It is probable that the other species of this group would show the same 
type of regeneration, if enough specimens were examined, since they are so closely 
related to the species in which these regenerations are known to occur. 
Part IJ. QuantirativE Data. 
This section deals with several large collections of each of three species; in 
each case all of the specimens caught at a given time and place were preserved. 
Most of these collections were made by Dr. C. H. Eigenmann, in British Guiana 
in 1908, and the others by the writer in the same country in 1910. The three 
species considered are Higenmannia virescens, Eigenmannia macrops and Sternopygus 
macrurus. In life they all closely resemble each other, not only in color but in 
size and shape. They are quite compressed and somewhat elongate. The body 
Fig. 29. Section showing location of air-bladder in Gymnotus carapo Linneus. 
tapers rather suddenly in the caudal region, which ends in a long, cylindrical caudal 
appendage, at least one-fourth as long as the entire body. The caudal appendage 
contains a continuation of the vertebral column, enclosed in a well-scaled sheath 
of skin. These fishes are so translucent that their blood gives them a distinctly 
red color. The epidermis is bright yellow, and beneath it are dark blue chroma- 
tophores, very abundant in S. macrurus, less so in EL. virescens, and almost wanting 
in H. macrops. 
In consequence of these peculiarities these species are capable of changing 
color to some extent. In proportion to the amount of blue pigment present they 
