of the Cacti in Brazil. 393 



to the animals. The horses often try to obtain refreshment 

 from the branches, by kicking off the spines with their hoofs. 

 These spines are nearly a span long on some species (perhaps 

 not yet well known to botanists), and they render the greatest 

 prudence necessary when on horseback, and pursuing a narrow 

 winding road. Where these species of Cacti grow in great 

 numbers together, a part of the vegetation of shrubs and low 

 trees generally disappears ; such as that produced by the genera 

 .Euphorbm, Tragm, Croton, Jatropha, Turners, .Echites, Big- 

 nonm, .Myrtus, Terminalia, Convolvulus, Cassalpinz'a, Erythroxy- 

 lon, Sida, Tillandsitf, Bromelza, Pitcairnzor, &c. ; and the eye 

 beholds nothing at a distance but the aspiring forms of the 

 leafless Cacti against the dark blue stormy sky. The exten- 

 sive deserts on both sides of the Rio de San Francisco, in the 

 provinces of Bahia and Pernambuco, which, taken at an average, 

 are from 500 to 1,500 feet above the level of the sea, consist of 

 a bare granite, void of earth, or of limestone formation ; and 

 similar districts in the northern provinces of Paraiba, Rio Grande 

 do Norte, and Ciara (those districts of Brazil in which the Cacti 

 most abound), are remarkable for their great accumulation of 

 sea salt, which oozes out of the ground after the rainy season. 

 Here and there are found large caves of saltpetre, and remains 

 of megalonyxes and mammoths, and in the chalk strata of Serra 

 dos Cagrires, there are petrified fish, which may be compared 

 with those of Solenhofen. These geognostical appearances arise 

 from the sea having formerly covered those parts, and, after its 

 sudden retreat, the loose earth becoming separated from the 

 stones, the lower animals inhabiting it were destroyed by the 

 dryness of the ground, and the scorching heat of the sun. 

 If such hypothesis could be proved, the Cacti (which, on ac- 

 count of their peculiar organisation, do not subsist so much 

 from the nourishment of the soil, as from the state of the atmo- 

 sphere), and other similar plants, such as liverwort, moss, &c, 

 might be considered as precursors of a more exalted race on a 

 more fruitful soil, like those leafless masses of gigantic plants 

 which are found, the relics of the antediluvian world. The dis- 

 tricts in which the Cacti are found at present in such abundance 

 enjoy without exception the clima mimoso, already mentioned : 

 and it has been observed that this climate is also favourable 

 for producing the finest cotton on the cotton plants ; while, in the 

 northern provinces of Maranhao and Para, though the plants 

 are strong, the cotton is not of so fine a quality. These plants, 

 also, are not cultivated where the Cacti grow, but in moist and 

 shady places. The chain of mountains of Ibiapaba, consisting 

 here and there of granite and strata of limestone, divides the 

 land of the Cacti from the western province Piauhy, a beautiful 

 hilly country, gently sloping towards the north-east, and in 



