152 
CASTLE OF SAN ANTONIO. 
Cumana, Coro, the island of Mkrgareta, and Curassoa, are 
the parts of South America that abound most in plants ot 
the nopal family. 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, 
hut also in the form of their articulated stems, the number 
of cost®, and the disposition of the thorns. \Ve shall see 
hereafter how these plants, which characterize a warm and 
singularly dry climate, like that of Egypt and California 
gradually disappear in proportion as we remove from the 
coasts, and penetrate into the inland country. 
Tbe groups of columnar cactus and opuntia produce the 
same eflect in the arid lands of equinoctial America as the 
juncese and the hydroeharides in the marshes of our northern 
climes. Places in which the larger species of the strong 
cactus are collected in groups are considered as almost im- 
penetrable. These places are called Tunales ; and they are 
impervious not only to the native, who goes naked to the 
waist, hut are formidable even to those who are fully clothed. 
In our solitary rambles we sometimes endeavoured to pene- 
trate into the Tunal that crowns the summit of the castle 
hill, a part of which is crossed by a pathway, where we could 
have studied, amidst thousands of specimens, the organization 
of this singular plant. Sometimes night suddenly overtook 
us, for there is scarcely any twilight in this climate ; and we 
then found ourselves dangerously situated, as the Cascabel, 
or. rattle-snake, the Coral, and other vipers armed with 
poisonous fangs, frequent these scorched and arid haunts, to 
deposit their eggs in the sand. 
The castle of San Antonio is built at tlie western extremity 
of the hill, hut not on the most elevated point, being com- 
manded on the east by an unfortified summit. The Tunal is 
considered both hero and everywhere in the Spanish colonies 
as a very important means of military defence; and when 
earthen works are raised, the engineers are eager to propa- 
gate j tlie thorny opuntia, and promote its growth, as they 
are careful to .keep crocodiles in the ditches of fortified 
places. In regions where organized nature is so powerful 
and active, man summons as auxiliaries in his defence the 
carnivorous reptile, and the plant with its formidable ar- 
mour of thorns. 
