1 62 Papers from the Marine Biological Laboratory at Tortugas. 



poorly preserved and so soft that when he cut the animal across its body, 

 the electroplaxes and connective tissue ran out of the muscle in which they 

 are embedded. Nevertheless Erdl stated that it was probably an electric 

 organ, coming to this conclusion by a comparison, of such features as he 

 could make out, with the structures found in the tails of the other electric 

 fishes, as Raja, Mormyrus, and Gymnotus. 



Fig. I. — General view of Gymnarchus nilolicus. (Drawn from a 

 lantern slide made from a figure in Jordan's "Guide to the Study 

 of Fishes," New York, 1905.) 



Fritsch (19) in 1885 worked on better material and gave a more com- 

 plete account of the anatomy of the organ, especially of the histology of the 

 electroplax; but he came to the rather strange conclusion that it was not 

 an electric organ at all, assuming the erroneous position that, on account 

 of the large blood-supply, the organ acted in some way as a storage for 

 oxygen during the period of hibernation made necessary by the drying of 

 waters at certain seasons. Fritsch was also mistaken in calling the fibrous 



^''^^VJV'i ' ""'*',"]' ' !''!'■ "/, / 







y. V 



Fig. 2. — Scene drawn from descriptions to illustrate the habitat of Gymnarchus and its manner 

 of swimming. (Drawn from lantern slide made from a drawing, by Bruce Horsfall.) 



contents of the electroplaxes "connective tissue." He went a great deal 

 farther than Erdl, however, in describing the gross anatomy of the electric 

 organs and surrounding tissues. 



Not having full-grown material, the writer must rely on Fritsch's figures 

 and descriptions for the adult gross anatomy, although the oldest embryos 



