176 MEMOIRS OF THE CARNEGIE MUSEUM. 



found to be correct. His second group contains all of the long-mouthed forms, 

 Sternardiorhynchus, Sternarchorhamphus and Rhamphichthys. These he thinks 

 must feed on insects. In this he was mistaken. The stomachs of these species 

 which were examined contained mud-inhabiting forms. His third group includes 

 the remaining Gymnotidce. He regards the toothless forms of this group to be 

 plankton-feeders, and cites Sternarchogiton and Steatogenys as examples. The 

 first mentioned was not examined. Three stomachs of the latter contained the 

 larvae of insects and Annelida as well as entomostraca, with Annelida much pre- 

 ponderating. The forms with teeth he gives as feeding upon small water-insects 

 and perhaps vegetable matter. Sternopygus was found to feed upon water-beetles 

 in particular, but also upon fish and freshwater shrimps. Eigenmannia on the 

 contrary took very few insects, but a great number of entomostraca and larvae 

 of insects. 



Summary. 



1. Entomostraca supplemented by the larvae of insects form the main food 

 of the young of all species examined. 



2. Only the adult large-mouthed species fed upon freshwater shrimps and 

 fishes. 



3. The adult small-mouthed species feed upon entomostraca, insect larvae, 

 and adult insects. 



4. The long tubular-mouthed species are bottom-feeders. Their food is 

 mud-inhabiting forms, Annelida, and insect larvae, sucked up with the surrounding 



mud. 



Reproduction. 



Nothing is known of the breeding habits of the Gymnotidce. Several unsuc- 

 cessful attempts have been made to obtain embryos or very small electric eels. 

 This failure has tended to confirm the belief of the natives that the electric eel 

 as well as the other Gymnotidce brings forth living young. But no Gymnotids 

 have ever been captured containing embryos, nor is the construction of the genital 

 tracts such as would favor this view, except in one particular. In most species 

 there is a more or less well developed papilla at the terminal opening of the sex 

 ducts just below the head. Sachs (116 et seq., 1. c.) was of the opinion that the 

 electric eel lays eggs. He collected several females with ripe eggs in February and 

 March. He thought the period of laying to be in the early part of the rainy season, 

 that is, the last of December and the first of January. Miller (Bull. Am. Mus. 

 Nat. Hist.; Vol. XXIII, 1907) states that he took many females of Gymnotus carapo 

 with eggs from the swamps and a sluggish stream near Los Amates, Guatemala, 

 on Feb. 20, 1905. The largest of them was 200 mm. long. Among the specimens 

 of Eigentnannia virescens and Sternopygus macrurus collected by Dr. C. H. Eigen- 

 mann in Georgetown are many females with eggs. Several females of Eigenynannia 

 are very noticeably distended. Some of the specimens which I took from the 

 same place on Sept. 26, 1910, contained eggs, but they did not seem as nearly ripe 



