478 



PARENTAL CARE AMONG FRESH-WATER FISHES. 



optiei, forcing them asunder, repressing them to the basal part of 

 the brain, and then to spread out in all directions, covering over and 

 concealing every one of the remaining portions of the brain." So 

 Sanders explains the structures in question. AVith these exceptions 

 " the other parts of the brain have very nearly the same structure as 

 in the ordinary Teleostean fishes." 



The Mormyrids are interesting for another reason : They are of 

 the number of electric fishes. On each side of the tail are peculiar 

 muscle-like sti'uctures which were named " pseudo-electric " long 

 ago, and which the researches of modern physiologists, especially 

 Babuchin and Gustav Fritsch, have demonstrated to be real electric 

 organs. These organs are in the form of oblique bands (like the 

 muscular segments from which they are derived), composed of small 

 columns perpendicular to their axis. They have little efficiency 

 compared with the electric apparatus of the electric catfishes, but 

 they are electric all the same, and they are developed to such an 



Pig. 58. — Pctroccij'iiuluti banc. After Geoffiroy Saiut Hillare. 



extent as to largely replace muscles. Fritsch, in 1803, demonstrated 

 that " a transverse section of the tail of Mormyrus shows no con- 

 spicuous muscles, but in place of them electric tissue filling up the 

 entire space occupied by muscles in ordinary fishes. Of the mus- 

 cular apparatus there is nothing left except the longitudinal tendons 

 passing outside the electric organs from muscles placed anteriorly. 

 If these tendons were cut across the Mormyrus would be unable to 

 move its tail." 



THE MORMYRmS. 



The Mormyrids are numerous, about 120 species having already 

 been discovered in the fresh waters of the *■' dark continent." A 

 caudal fin is always manifest and the vertebrae are in moderate num- 

 ber — 37 to 64. An imperfect electrical apparatus is developed from 

 the caudal muscles. The species vary much in the form of the snout 



