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INDIANA UNIVERSITY STUDIES 



Very slender, tapering from head to caudal ; the caudal peduncle 

 • nearly twice as long as deep ; origin of dorsal equidistant from tip of 

 snout and end of middle craulal rays, the fifth and sixth rays longest, not 

 quite as long as head, the rays to the first and last graduate ; adipose 

 very minute ; caudal deeply forked, the lower lobe the longer, more than 

 a third of the length from s^^out to caudal, the lo\Yer fulcra separate, 

 forming a spur (?); anal unique among the characins, the last ray 

 prolonged, reaching to near second third of lower caudal lobe, the re- 

 mainder of the fin shaped like the dorsal, the highest middle rays a lit- 

 tle higher than the highest dorsal ray ; ventrals trunc:\te. fan-shaped, the 

 tips of the rays protruding, the inner ray prolonged, reaching the base 

 of the thirteenth anal ray; pectorals lanceolate, placed low, reaching to or 

 nearly to the ventnils. 



Mouth very oblique, second suborbital covering the entire cheek; gill- 

 membranes united, free from the isthmus ; premaxillary w^ith four teeth 

 forming an'^rregular outer series and four larger ones forming an inner 

 series; maxillary with tw^o teeth. Mandible with three large teeth in 

 front, abruptly smaller ones on the sides. 



Sides peppered ; an oval black spot just above the base of the last 

 anal rays, a streak from this toward caudal nearly free from chromato- 

 phores ; a similar black spot at base of upper caudal rays. 



A scale on the left side of the body, the third from the median dorsal 

 series and about the seventh from the head, prolonged into a slender 

 rod nearly oiie-third of the length from snout to caudal, reaching to near 

 the origin of the anal where it is expanded into a two-lobed, black-margined 

 flap; the corresponding scale on the right side of the body is broad and 

 spatulate but not unduly prolonged ; caudal naked, the scales at the baso 

 of the lower lobe forming a pouch. 



Named for Mr. Hugh McK. Landon of Indianapolis, Indiana, who in 

 large measure has made possible a second expedition into the Choco 

 regions of Colombia. 



