130 MEMOIRS OF THE CARNEGIE MUSEUM. 



Body and head compressed; width of the head 2.25 to 2.4, depth of the head, 

 at base of the occipital process, 1.5 to 2 in the greatest depth; anus on or slightly 

 behind the vertical from the posterior margin of the eye; dorsal profile regularly 

 and moderately convex; ventral profile varying from rather weakly convex to 

 markedly so. 



Snout heavy, short and blunt; mouth moderate; gape short to medium; jaws 

 about equal, the lower included on the sides, teeth present in both jaws; eyes small 

 to medium. Caudal peduncle 3.25 to 4.75 in the total length; origin of the anal 

 below, or slightly behind, the origin of pectorals; pectorals about 1.2 in the head. 



Ground color of alcoholic specimens, buff; dorsal and dorso-lateral parts more 

 or less overlaid with greenish brown, belly lighter; the lateral line and three stripes 

 which parallel it dark (any or all of these stripes which are ventrad to the lateral 

 line may vary considerably in width and intensity, may even be wanting) ; a black 

 bar at the origin of each anal ray; fins hyaline; caudal peduncle blue-gray above 

 and pale yellow below. 



In life Eigenmannia virescens is quite translucent, and is of a bright reddish 

 color. The head and pectoral regions are orange to yellow and the caudal append- 

 age greenish. This species is capable of changing color to some extent (See dis- 

 cussion of color). 



The markings of the different individuals vary considerably according to the 

 presence or absence of the dark blue stripes above the anal fin. Specimens from 

 clear water usually show well developed stripes and have the head much darker 

 than those found in muddy water, and may have the anal fin fringed with dusky. 

 The chromatophores are more numerous over the entire body of those from clear 

 water. 



This species is classed among the food-fishes, though it is not much sought 

 after by the white people. The coolies of British Guiana seem particularly fond 

 of this fish, which, with the other Sternopygince, they call the "Loga-Loga." In 

 addition to the name "Cuchillo" or "Cuchilla" applied to it by most Spanish- 

 speaking Creoles, it is known as "Macana" and "Raton bianco" in the United 

 States of Colombia and Venezuela, and "Tuviras" in Brazil. It is found abund- 

 antly in the trenches and ditches on the plantations, where it feeds among the 

 weeds. Its natural habitat is in the small streams which flow through savannah 

 or open country in the lowlands. 



Because of its large range several varieties have been described as separate 

 species, but these intergrade. " Humboldti" of Steindachner may be a distinct 

 variety. It is found along the west coast and in the Rio Magdalcna system. 

 Specimens answering its description have been taken in Guiana and Brazil. 



Distribution: Rio Magdalena and west coast south over the whole of eastern 

 South America to the Rio de la Plata. 



