550 TELEOSTEI CHAP. 
like Gymnarehus may have been evolved out of a more typically- 
formed Fish. Nothing is more striking than the variation in 
shape of the snout within one and the same genus, and the names 
given to some of the species (ovis, caballus, elephas, tamandua, 
numenius, wbis) are sug- 
gestive of resemblances 
with the heads of various 
aninals. 
The Mormyrids are 
highly remarkable for the 
enormous development of 
the brain, the weight of 
which equals =1, to x, of 
the total, a thing unparal- 
leled among lower Verte- 
brates; and for the pro- 
blematic organ which 
surmounts it ; also as being 
among the few Fishes in 
which an electric organ 
has been discovered. The 
Fia. 331.—Head of Gnathonemus numenius. 
organ, situated on each side of the caudal region, is derived from 
the muscular system and is of feeble power, as ascertained by 
Babuchin and by Fritsch; it was long considered as “ pseudo- 
electric.” The natural affinities of this family appear to be with 
the Albulidae, and there is nothing to justify the term “ Nil- 
hechte ” (Nile-pike) which has been bestowed on them by German 
