94 FISHES. 



filled by an embryonal muscular substance which contains 

 a large quantity of fat and blood-vessels, and therefore 

 differs from ordinary muscle by its softer consistency, and 

 by its colour which is reddish or grayish. Superficially the 

 lateral muscle appears crossed by a number of white parallel 

 tendinous zigzag stripes, forming generally three angles, of 

 which the upper and lower point backwards, the middle one 

 forwards. These are the outer edges of the aponeurotic septa 

 between the myocommas. Each septum is attached to 

 the middle and the apophyses of a vertebra, and, in the 

 abdominal region, to its rib; frequently the septa receive 

 additional support by the existence of epipleural spines. The 

 fibres of each myocomma run straight and nearly horizontally 

 from one septum to the next ; they are grouped so as to form 

 semiconical masses, of which the upper and lower have their 

 apices turned backwards, whilst the middle cone, formed by 

 the contiguous parts of the preceding, has its apex directed 

 forward ; this fits into the interspace between the antecedent 

 upper and lower cones, the apices of which reciprocally enter 

 the depressions in the succeeding segment, whereby all the 

 segments are firmly locked together {Owen). 



In connection with the muscles reference has to be made 

 to the Electric organs with which certain fishes are provided, 

 as it is more than probable, not only from the examination of' 

 peculiar muscular organs occurring in the Eays, Mormyrus, 

 and Gymnarchus (the function of which is stiH conjectural), 

 but especially from the researches into the development of 

 the 'electric organ of Torpedo, that the electric organs have 

 been developed out of muscular substance. The fishes 

 possessing fully developed electric organs, with the power of 

 accumulating electric force and communicating it in the 

 form of shocks to other animals, are the electric Eays 

 {Torpedinidm), the electric Sheath -fish of tropical Africa 

 (Malapterurus), and the electric Eel of tropical America 



