Cee 
262 BOTANICAL GAZETTE. [ October, 
and contraction of form would be characteristic of the flora. 
The attempt to make an analysis of one’s feelings on being 
somewhat unexpectedly brought face to face with this pecul- 
jar vegetation would be futile, as no point of comparison ap- 
pears to offer. The giant Cereus occupies the _hill-sides 
ened tissues show that they, too, have the impress of the 
dry, hot air about them.” One of the most conspicuous of 
resinous matter on the branches. It is reputed to have 
strong medicinal virtues. Several kinds of Rhamnaceous 
shrubs also are frequently met with, among them species of 
Zizyphus and Karwinskia. The order Leguminose has a 
pretty abundant representation in peculiar species in the des- 
ert region, particularly the genera Astragalus, Galea, Cassia, 
Acacia and Mimosa. 
Cereus to the various forms of flat-branched and cylindrical 
Opuntias, intermixed with Mamillarias and Echinocact! 1) — 
great number. Cereus giganteus, or the tree cactus, attains 
a height of from twenty to fifty feet, and is probably half @ 
