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POPULAR SCIENCE MONTHLY 



11. Adaptive Radiation in the Chaeacisid.e. The central figure of Astyanax bimac- 

 latus with notched teeth probably represents the more primitive condition. The lower left- 

 hand figure represents Anodus Intior with no teeth and a very long alimentary canal, a mud 

 eater. The lower right-hand figure represents the scissor-like jaw and teeth of Serrasalmo 

 humeralis whose relatives have been repeatedly reported to have killed bathers before they 

 could reach shore after being attacked. The upper figure represents Ftaphiodon vulpinus Spix 

 which has reached the extreme in conical teeth, the large canines protruding above when the 

 jaws are closed. The over 100 South American genera and 500 species of this family offer pretty 

 complete series from the center to the extremes with many lateral branches. 



