A STUDY OF THE SUBMENTAL FILAMENTS CONSID- 
ERED AS PROBABLE ELECTRIC ORGANS IN THE 
GYMNOTID EEL, STEATOGENYS ELEGANS (STEIN- 
DACHNER) 
ANNA LOWREY 
Biological Laboratory of the University of Colorado 
FOUR FIGURES 
INTRODUCTION 
Specimens of Steatogenys elegans (Steindachner) are very 
rare, since this fish is found only in the tropical rivers of South 
America. The seven specimens used in this study were obtained 
by the Gimbel Expedition to British Guiana in 1910. They 
were caught in the Demarara river by a native woman. 
The submental filament consists of a series of saucer-shaped 
dises, placed parallel to each other, surrounded by a cylindrical 
sheath of connective tissue, and with a large nerve running be- 
tween these discs and the sheath. From the minute structure of 
the discs, and from the relation of the nerve to them, it seems 
that these dises are electroplaxes, and that each submental fila- 
ment is an electric organ. 
TECHNIQUE 
The fishes were killed in formaldehyde and 85 per cent alcohol. 
The submental filaments were embedded in 56° C. paraffin, and 
serial sections, six micro-millimeters thick, were made. Both 
transverse and sagittal series were examined, the two filaments 
for comparison being from the same fish. All sections were stained 
by Heidenhain’s iron hematoxylin method and counter stained 
with licht griin. 
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JOURNAL OF MORPHOLOGY, VO L. 24, No. 4 
