l6o EIGENMANN AND WARD 



Several species are found in the Paraguay and Amazon rivers 

 which have not been reported from as far south as the La Plata. 

 These are Hypopoinus brcvii'ostris from the Cauca to Para and 

 Paraguay, Stcrnarchiis alhifrons and Gymnotus carajyiis from 

 the Orinoco through the entire course of the Amazons from 

 Peru to Para and to Paragua}'', and Rhamphichthys 7'cinhardti 

 which is not found north of the Amazons. 



The place where more collections have been made than else- 

 where and which must serve as an index of the abundance of 

 the South American fish fauna is Manaos, or Barra do Rio 

 Negro. At this place or in its neighborhood 12 of the 29 species 

 have been taken; 21 species have been taken in the Amazons 

 but not more than 14 in any one of its 3 sections. The ac- 

 companying geographical table will give an idea of the abun- 

 dance of local faunas or the thoroughness with which collecting 

 has been done. Fifty species have been described, of which 

 29 seem to be valid. 



KEY TO THE GENERA OF GVM.VOTID.4i:. 



a. Caudal fin present ; eye without free orbital margin ; a large fon- 

 tanel ( Sternarchincc. ) 



b. Snout not producec], the eye nearer tip of snout than to gill- 

 opening. 

 c. Both jaws with teeth, tliose of the lower jaw in 2 series, those 

 of the upper in 3 or more series. 

 d. Gape long, the angle of the mouth but little if any in front 



of eye; snout long Sternai-chus^ i« 



dd. Gape short, the angle of the mouth below the anterior or 



posterior nostrils; snout short Sternai-cheUa^ 2. 



cc. Upper jaw without teeth, those of the lower jaw in a single 



series; snout very short Sternaj'c/iogiton^ 2>' 



hh. Snout produced, the eye nearer the gill-opening than to tip of 

 snout ; anal long. 



e. Snout straight, the gape moderate SteruarchorhainpJiits^ 4. 



ce. Snout strongly decurved ; mouth minute, the gape about twice 



length of eye Sicruarc/iorZ/ync/ms^ 5. 



aa. No caudual fin, the tail ending in a point. 

 f. A large fontanel ; vent below the head. 



' If Peter's description of S(crna>x/ius sacJtsi is correct and sachsi does not 

 contain teeth in either jaw, it should stand as the type of a new genus. 



