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Indiana University Studies 



The Pceciliidse and fresh-water Mugilidae are more distinctly 

 Central American types than the Gobiidse, and the Chagres 

 certainly got some of its genera of these families from the north, 

 either by sea or by land. None of the genera of these families 

 find their farthest north in the Chagres and only a few of the 

 genera of the Pceciliidse extend farther south than Panama. Their 

 ancestors most probably came from the north. 



Remain then the Siluridse, Loricariidae, Gymnotidae and Cich- 

 lidae. 



Of the Siluridae, Rhamdia wagneri and Pimelodella chagresi 

 represent the farthest north of genera everywhere on the Atlantic 

 slope from Buenos Aires north and on the Pacific slope at least 

 from Guayaquil north. The ancestors of these species undoubt- 

 edly came from the south. The Chagres species are common at 

 least as far south as the Magdalena. 



The Loricariidae flourish everywhere in South America north 

 of Guayaquil and Buenos Aires and the ancestors of all four 

 of the Chagres species came from the south and found their 

 farthest north in the Chagres. Only one member of the family, 

 Ancistrus aspidolepis, has gotten as far as northern Panama. 



Of the Characidae, the Cheirodontinae 6 , Piabucininae, and 

 Erythrininse find their farthest north m the Chagres. The 

 Glandulocaudmae reach Costa Rica; the Bryconmae and Chara- 

 cinae reach Guatemala. Only the Tetragonopterinae attain the 

 United States. The Chagres undoubtedly got the ancestors of 

 all of its Characins from the south. 



The Cichlidae have undergone an elaborate evolution in Central 

 America and Mexico as well as in South America, and there is 

 evidence that the Cichlid fauna of the Chagres came in part 

 from the north and in part from the south. The genera Geophagus 

 and Aequidens universally distributed betwen Buenos Aires and 

 Colombia find their farthest north in the Chagres, and the an- 

 cestors of Geophagus crassilabris and Aequidens coeruleopunctatus 

 came from the south. The genus Neetroplus, on the other hand, 

 is a Central American product. One species inhabits Nicaragua, 

 one Costa Rica, and the third the Chagres. The genus reaches 

 its farthest south in the Chagres, and the ancestors of N eetroplus 

 panamensis may very well have come from the north. The same 

 is true of Cichlasoma maculicauda, which finds its farthest south 

 in the Chagres. 



6 With one exception? 



