ANNOTATED LIST OF THE SPECIES 331 
among them one of two feet in length which had been a pet or a curiosity in a cistern 
of a monastery cloister for fifteen years. 
In the spirit of Faraday’s experiment in which he used the discharge to ignite 
gunpowder or to charge Leyden jars, Coates and Cox have resumed physical studies 
of the fish with the more refined methods of modern apparatus. Cox (1938) has 
shown from his field and laboratory studies that the minor electroplax of the fish 
differs from the major electric organ in that it delivers a low, constant discharge 
while swimming, which may be either a warning or a protection. He finds also 
that the fish not only discharges electricity, but is sensitive to it as well. He was 
able to use a hand-generator, with the positive and negative plates in the water, as 
a lure, the fishes being attracted to the positive pole. These workers have made 
studies of the character of the electric discharge, its control, its volume, duration, 
and like matters. They have been able to register voltages up to nearly 600, and 
wattages up to 1000, but over such brief periods of time that the filaments of lamps 
could not reach incandescence. 
Haseman’s experiences may help to explain the degrees of potency of the elec- 
tric discharge (1911b). An Indian had shot a purakee five feet long, with bow and 
arrow, the same length as the one which Herndon discusses. _Haseman swam after 
the specimen and pulled it ashore. While the fish yet had the tail in water, he was 
able to pass his hand over it repeatedly. The shock was acute, but not over- 
powering. Then while removing it with a copper dipnet from the water, “I received 
all its voltage, and fell helpless in the moist sand. A series of terrible shocks con- 
tinued as long as the eel remained on my bare legs, and I could not let go the dipnet. 
The Indian relieved me by pulling the eel away by means of the arrow.”” Haseman 
is convinced that the electric organ is nothing more than a protection, for he has 
seen no evidence of its ever being used offensively for taking prey. 
Ellis’s studies of the Gymnotid family led him to regard the lower Amazon as 
the center of its dispersal. The present report, in which we list about the same 
number of species for Peruvian waters as Ellis lists for all South America, would 
encourage the view that the center of dispersal is farther up the Amazon than he 
had reason to believe (1913). 
Order SYMBRANCHIA 
Family XIII: Symbranchidae 
Genus 187: SYMBRANCHUS Bloch 
Synbranchus Bloch, 1795, Ausl. Fische., IX, 86; 
Eigenmann, 1910, Rept. Princeton Univ. Exped. Patagonia, IIT, 450. 
Symbranchus (corrected spelling) most authors; 
Higenmann, 1912, Mem. Carnegie Mus., V, 442; 
Eigenmann, 1922, Mem. Carnegie Mus., LX, 177. 
Type: Synbranchus marmoratus Bloch 
Range that of the one species 
Anguilliform, sealeless; tail shorter than trunk; right and left gill-membranes 
joined in midventral line, forming a single, small, median ventral gill-aperture. 
