THE GYMNOTID EELS OF TROPICAL AMERICA. 169 



it was free-swimming. It is probable therefore that most of tlic food is taken 

 while it is moving. 



Electrophorus ELECTRicus (Linnaeus). 



Snout moderate and blunt; conical teeth in both jaws; mouth large; size up 

 to seven feet. 



No stomachs of this species were examined. From the references given below 

 its food seems to consist for the most part of small fishes and freshwater shrimps. 

 The data are for large eels only and in two or three instances show the kinds of 

 food which is taken when in captivity, rather than the normal food as chosen by 

 the free fish. The authority is stated and followed by the food mentioned. 



Sachs, Zitteraal, p. 108: "especially freshwater Crustacea, also small fish, 

 small crayfish, many insects, and grasshoppers." 



Flagg, Trans. Am. Philos. Soc, Vol. ii, p. 172: "Its common food is shrimps 

 or any small fish." 



Garden, Trans. Am. Philos. Soc, 1775, p. 110: "Small fish, also any animal 

 food if it is cut so they can swallow it." 



Faraday after Humboldt, Experimental Researches, 1753, p. 3: "Boiled 

 meat and bread, small fish." 



Sachs, /. c, 110: "Nothing dead, except dead fish." 



Sternopygus macrurus (Bloch and Schneider). 



Snout rather blunt; minute teeth in patches in both jaws; mouth moderately 

 large; size, up to 500 mm. 



Sternopygus macrurus (Bloch and Schneider). 



The contents of twenty-nine stomachs of this species were examined. Three 

 items are found distributed in the table much as in the table given for G. carapo, 

 namely: fishes, malacostraca, and entomostraca. The first two were eaten only 

 by the fish above 290 mm. in length, while the last named were only in the stomachs 

 of specimens less than 100 mm. in length. The most noticeable difference between 

 the food of G. carapo and S. macrurus is the amount of insects consumed by the 

 latter. Adult insects form the major portion of the food, not only of the medium- 

 sized individuals, but of the eels above 100 mm. long. Four hundred and three 

 adult insects were counted, of v/hich three hundred and twenty-one were aquatic 

 Coleoptera (for the most part Gyrinidoe) ; seventy-five aquatic Heniiplera (Corisldse 

 and Notonectidse) ; four terrestrial Coleoptera (Carabidse) ; three terrestrial Hemip- 

 tera (Reduviidse and Pentatomidae) . They are all surface-forms or land-forms 

 which could easily reach the water. The eighty-two insect larvae were identified 

 as follows: fifty-three Diptera; one Odonate; twenty-one Trichoptera, and seven 

 doubtful. Seventeen fishes (Characins), one Amphipod, three Isopods, and three 

 freshwater shrimps with fourteen entomostraca made up the rest of the food. 

 The main food of medium-sized specimens is adult insects. In two larger indi- 



