204 BOTANICAL GAZETTE [OCTOBER 
AVERAGE CONCENTRATION IN COASTAL DESERTS.—As a pre- 
liminary to any further analysis of these data the average values 
for the two habitats and the different growth forms must be 
obtained. 
For the 5 arborescent species of the coastal flats the general 
average is given by 
Caesalpinia A=2.95, P=35.4 
Capparis A=3.76, P=45.0 
Capparis A=4.12, P=49.3 
Guaiacum A=4.35, P=52.1 
Prosopis A=2.53, P=30.3 
General average 3.542 42.42 
The 3 species of the coastal flats which have been classified 
as dwarf shrubs differ greatly in concentration. Achyranthes is a 
rather hard-leaved halophyte which does not penetrate to the most 
saline spots. It is characterized by a concentration of about 34 
atmospheres as compared with about 50 atmospheres in the highly 
succulent Batis maritima, the sole species found in the more saline 
spots. Sesuvium Portulacastrum is characteristic of only the less 
saline portions of the flats, and shows a far lower average concentra- 
tion, although some of the individual values attain about the 
average for Batis. 
The actual averages are: mean depression, 2.737°; mean con- 
centration, 32.80 atmospheres. 
For the more truly arborescent species of the rocky slopes the 
values are: - 
Bauhinia A=3.04, P=36.5 
Caesalpinia A=2.26,'P=27.2 
Canella A=3 18, P=38.1 
shen A=3.58, P=42.9 
sia A=1.97, P=23.6 
Sean A=1.49, P=18.0 
Melicocca A=1.87, P=22.4 
Prosopis A=2 69, P=32 3 
Sarcomphalus A=1 63, P= 19 6 
Schoepha A=2.79, P=33.5 
Tamarindus A=1.75, P=21.0 | 
General average 2.388 28.6 
