INTRODUCTION. Ixix 
scribed species, to which he gave the name of Pinus ca- 
nariensis ; discovered a new species of Ardisia, and col- 
lected many other new and interesting plants. Several 
botanical travellers have noticed the singular appearance 
of the roofs of the houses of Laguna, from their being co- 
vered with a sort of house-leek, bat none had described 
it. Mr. Smith, on examination, found it to be a new spe- 
cies, and named it, from its situation, Sempervivum 
urbium. 
From Santa Cruz the travellers passed near to Palmas, 
the capital of Grand Canaria. It was now the month of 
August, and the summer heat had parched the earth and 
dried up the plants, excepting some Euphorbias and 
others of the succulent tribe. They, however, determined 
by the barometer, for the first time, the height of Pico del 
Pozo de los Nieves, the most elevated on the island, to 
be 6224 English feet above the level of the sea. 
On returning to Santa Cruz, Smith and his friend set 
out on a journey to the Peak of Teneriffe, along the crest 
of the mountain which crosses the island in its greatest 
length. Near the summit of the peak the two naturalists 
passed several days, traversing the immense stream of 
Obsidian, which encircles its western side, examined the 
volcano of Chahorra, remaining in the mountains till forced 
down from want of food, water, and shoes, the latter of 
which were fairly cut in pieces by the glassy lava. Em- 
barking at Oratava, they proceeded to the Isle of Palmas ; 
examined the immense and almost inaccessible crater, 
which occupies the centre of the island ; ascended the Pico 
de los Muchachos, whose height was found to be 7707 
English feet, and which commands a view of the whole 
