A DRY EQUATORIAL DISTRICT. 171 



however, " in (the town and province of) Ceara alone, 

 above half a million, or more than one half the popu- 

 lation, died."* 



If so great a mortality could occur in the present 

 age in spite of the advance of modern science and 

 knowledge, what might not have taken place during 

 the dark ages when the grossest ignorance and super- 

 stition prevailed! 



If we proceed to seek for an explanation of so great 

 an apparent anomaly as the occurrence of this dry 

 desert region, existing in the moist and rainy equa- 

 torial zone, the only reason that can be assigned for 

 it seems to be that suggested by Mr. Wallace "that 

 the sandy soil and bare hills produce ascending currents 

 of heated air, which prevent condensation at this 

 point." f 



Anomalies of this kind, however, will be found to 

 occur in each of the terrestrial zones, as islands appear 

 here and there to rise above the surface of the ocean, 

 or a fertile oasis is found to exist in the midst of the 

 desert. 



We must next turn our attention to the consideration 

 of the primeval forest, which constitutes the charac- 

 teristic feature of the equatorial zone, and covers by 

 far the greater proportion of its surface. 



It would indeed require the pen of a ready writer 

 to do justice to, or even to attempt to portray, in 

 adequate terms, the magnificence, and the marvels of 

 these great, almost boundless, wildernesses of tangled 

 vegetation ; where gigantic trees, and creepers of every 



* Brazil, the Amazon and the Coast, by Herbert H. Smith, 1880, 

 p. 410. 



f See Tropical Nature, by Alfred R. Wallace, 1878, p. 19. 



