XI 



ELECTRICAL FISHES 



The Electrical Cat-fish (Malapterurus electricus), the iiaasch of 

 the Arabs, which inhabits many of the rivers of Central Africa, is 

 an exception to the other electrical fishes, inasmuch as its powerful 

 batteries are not due to the transformation of striated skeletal 

 muscle-fibres, but are localised in the skin, which is in conse- 

 quence transformed into a thick, transparent, speckled rind, which 

 loosely invests the greater part of the trunk, and causes the 

 animal to look bulky and shapeless. This peculiarity expresses 

 itself internally in parallel folds of the skin, during sideway 



FIG. 258. Particle of skin of Malap- 

 terurus seen from above ; magnified. 

 (G. Fritsch.) 



FIG. 257. T.S. through trunk of Malapterurus. 

 m muscles; = organs. (G. Fritsch.) 



movements of the body. In cross-section it is evident that this 

 rind invests the body proper like a sack, and is separated from 

 the muscular surface by an excessively loose tissue (the so- 

 called integument of Eudolph), so that it is easily drawn off 

 (Fig. 257). Between the epidermis proper and the internal, 

 tendinous boundary of the rind there is in the fresh state a 

 transparent, gelatinous mass of a clear yellow-gray colour, which 

 is unequal in consistency, but entirely absent in a few places 

 only. In the older specimens two longitudinal partition walls 

 running dorsally and ventrally in the middle line divide the 

 brawn -like intermediate mass symmetrically into two hemi- 



