466 



cation takes place at the boundary of two basins^ 

 and this boundary passes through the bed of the 

 principal recipient, the branch that runs off es- 

 tablishes an hydraulic communication between 

 two systems of rivers, and fixes our attention the 

 more in proportion as it is broader and more 

 navigable. The Cassiquiare is two or three 

 times broader than the Seine near the Jardin 

 des Plantes ; and to show how remarkable this 

 river is, I shall mention % that, on seeking care- 



Oroonoko, the Rio Magdalena, and the Ganges j 2dly, deltas, 

 on the shore of inland seas, like those of the Oxus, and of the 

 Sihon, or Sir - } 3dly, deltas of tributary streams, like those at 

 the mouth of the Apure, the Arauca, and the Rio Branco. 

 When several secondary rivers are formed in the vicinity of 

 the deltas of tributary streams, all that is observed on the shore 

 near Oceanic deltas takes place in the inlands ; the nearest 

 branches communicate their waters to each other, and form 

 a net-work of rivers, that can with difficulty be recognized in 

 the time of great inundations. On an extraordinary inter- 

 branching with a counterslope, see above, p. 377. 



* I take into consideration only the communication be- 

 tween two systems of independant rivers (that is, of rivers 

 both of which flow into the Ocean), and I suppose, that these 

 communications take place far from the shore, by means of 

 a branch that issues from one of the principal recipients to 

 fall into the other, either directly, or by joining a tributary 

 stream. I exclude consequently Oceanic bifurcations or deltas; 

 branches which a river near the coast sends to another river 

 flowing into the Ocean very near the former ; the numerous 

 examples of communications of rivers observed in the inlands 

 between two tributary streams of the same river ; finally, the 

 lakes or marshes situate on a line of ridges between two 



