eigenmann: tetragonopterid characins. 103 



Third tooth of the outer series of the premaxillary entirely ■withdrawn from the 

 line of the rest. 



A black line along base of anal ; a faint dark line along the sides, otherwise 

 faintly silvery, without spots. 



One specimen, 40 mm. (to base of caudal). Tabatinga. 



Moenkhausia australe, sp. nov. 



Differs from oligolepis in number of scales in the lateral line, 24-26. 

 Two specimens, 33-41 mm. long. Arroyos Trementina and Chagalalina. 

 One of the few species of this genus extending south of the Amazon. 



Moenkhausia barbouri, sp. nov. 1 



Very similar to M. heterolepis, the striae of the scales different and the caudal 

 lobes dark. 



Head 4.2-4.3 ; depth 2.4; D. 11 ; A. 30-33. 



Compressed, moderately deep ; dorsal and ventral profiles symmetrically curved. 



Four or more diverging striae on each of the lateral scales. 



A faint, vertical humeral spot ; tips of caudal lobes and middle rays faintly 

 dusky ; a well-defined silvery lateral band two-thirds as wide as the eye ; sides 

 iridescent silvery. 



Two specimens, 62 and 66 mm. Villa Bella. 



Moenkhausia dichrourus intermedius, subsp. nov. 



These typically colored specimens have a slender maxillary whose anterior 

 margin is not greatly arched ; the premaxillary has a much greater anteroposterior 

 extent than in typical dichrourus. Occipital process \ the space from its base to 

 the dorsal. 



Two specimens, 42 to 64 mm. Tabatinga. 



Moenkhausia lepidurus latus, subsp. nov. 



These specimens differ from others from the Tapajos, and from various other 

 localities. Anal rays average 26+. Body deeper, the depth averaging 2.6 of the 

 length. 



Middle caudal rays faintly colored, if at all ; upper caudal lobe black. 



Many specimens, 55 to 75 mm. Rio Tapajos. 



Moenkhausia lepidurus icae, subsp. nov. 



Deep, compressed ; depth 3 ; anal rays usually 23 or 24. 



Upper caudal lobes and sometimes distal part of other rays dusky ; a very 



1 For Mr. Thomas Barbour of Cambridge. 



