HASEMAN, GEOGRAPHICAL DISTRIB VTION IN SO VTH AMERICA 63 



occasionally is taken from salty water. I put this species directly out of 

 fresh into a bucket full of sea water. It was able to live several hours 

 under these conditions. 



Sao Francisco and the Secca (Dry) Region of Northeastern 



Brazil 



This region is characterized by desert-like flora, no forests, scanty rain- 

 fall and occasional long dry seasons during which many rivers become 

 dry. The altitude is medium (246 m. at Jatoba above the Paulo Affonso 

 Falls). 



This region harbors the following species of the cichlid fishes : 



Cichlosoma bimaculatam, 30 

 Crenicichla lepidota, 

 Geophaffiis brasiliensis. 



It is interesting to note that the above three genera are also the only 

 three which are found in Eio Grande do Sul, where, in place of having 

 the same three primitive species, six new more cenotelic species have 

 evolved from the above three more generalized widely distributed forms. 

 The only explanation is that the environment of the muddy semi-arid 

 Eio Sao Francisco has not been conducive to either the production or the 

 maintenance of new species, because the original species were identical 

 for both of these environmental complexes, i. e., they came from the same 

 ancestral highland stock. 



The Paraguay as Part of the Amazonian Complex 



The great swamps, called pantanals, of tbe Paraguay are in all respects 

 the exact southern counterpart of part of the Guapore and the central 

 portion of the Amazon basin. Their similarity must be great, because 

 they all lie in the confines of the central portion of the remains of the 

 Piano Alto. This is not true of either the Parana, Uruguay or Sao 

 Francisco rivers, as well as the Andean affluents of the Amazon. The 

 similarity is further very striking in altitude, while the Parana is three 

 or four times higher. Inasmuch, however, as the Amazon Valley is so 

 large, it duplicates several times the natural conditions found in the 

 Paraguay as well as in several other rivers. This duplication includes 

 temperature, altitude, food, volume of water, swamps, nature of currents, 

 humidity, rainfall, nature of sediment and muddy and clear water. 



30 I collected two specimens with three anal spines which were exactly like JEquitiens 

 portalegrensis. 



