singular appearance. Near Maniquarez, at 

 Punta A ray a, we measured a cactus, the trunk 

 of which was four feet nine inches in circumfe- 

 rence*. A European acquainted only with the 

 opuntia in our hot-houses is surprised to see the 

 wood of this plant become so hard from age ? 

 that it resists for centuries both air and mois- 

 ture, and that the Indians of Cumana employ 

 it in preference for oars and door posts. Cu- 

 mana, Coro, the island of Margaretta, and 

 Curassoa, are the places of South America that 

 abound most in plants of the family of the no- 

 pals. There only a botanist after a long resi- 

 dence could compose a monography of the 

 genus cactus, the species of which vary not 

 only in their flowers and fruits, but in the form 

 of their articulated stem, the number of costae, 

 and the disposition of the thorns. We shall see 

 hereafter how these plants, which characterize 

 a warm and extraordinarily dry climate, like 

 that of Egypt and California, gradually disap- 

 pear in proportion as we remove from the coasts, 

 and penetrate into the inland country. 



The groups of cactus and opuntia produce 

 the same effect in the arid lands of equinoxial 

 America, as the juncese and the hydrocharides 

 in the marshes of our northern climes. A place 



* Tuna macho. We distinguish in the wood of the cactus 

 the medullary prolongations, as Mr. Desfontaines has already 

 observed (Journ. de Physique, t. xlviii, p. 153), 



