550 



TELEOSTEI 



like Gymnarchus 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, ibis} are sug- 

 gestive of resemblances 

 with the heads of various 

 animals. 



The Mormyrids are 

 highly remarkable for the 

 enormous development of 

 the brain, the weight of 

 which equals -g^ to -^ 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 



FIG. 330. Head of Gnathonemus curvirostris. n &S been discovered. The 



FIG. 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 



