278 



EXICO, CENTEAL AMEEICA, WEST INDIES. 



when Lakes Nicaragua and Managua formed a continuous basin which sent its 

 overflow to the Pacific at the Gulf of Fonseca. From that epoch dates the intro- 

 duction of the marine species, which have gradually adapted themselves to the 

 fresh waters of Lake Nicaragua. 



Gil Gonzalez de Avila was assured by the natives that Lake Xolotlan (Man- 

 agua) had an emissary flowing directly to the " Gulf of Chorotega " (Fonseca), 

 but that the outflow was arrested by a lava stream from Momotorabo. The 

 emissary is now represented by the Estero Real, while Managua sought another 

 issue southwards to Lake Nicaragua, and thus became a tributary of the Atlantic. 



A slight upheaval would still suffice to convert Managua into a closed basin. 



Fig. 121. — Marrabios Range and Lake Managua. 

 Scale 1 : 1,400,000. 



30 utiles. 



During the rains it feeds an emissary which at the Tipitapa salfo has a picturesque 

 fall of 17 or 18 feet ; but in the dry season there is no continuous current, the 

 water slowly percolating through the sands and fissures of the rocks. A dry 

 space of over four miles separates the outflow from the estero of Panaloya, which, 

 although presenting the appearance of a river, is merely a tranquil backwater 

 communicatino: with Lake Nicaragua. 



Even during the rains Tipitapa is completely obstructed by reefs, and in 1836 

 Belcher had to transport a boat from one lake to the other. Hence it is all the 

 more surprising that projectors of interoceanic canals should represent Tipitapa as 

 the natural prolongation of a great transisthmian canal. Managua itself, although 

 over 400 square miles in extent, is obstructed by shoals, which render it 



